The operative concept is "love as a response to values."
Sex, not in all cases certainly, but in many nevertheless, is a consequence of emotions.
Emotions come from many places. Some, I think it can be said, are innate. Others, however, serve as a sort of instant summary of ideas we hold in our mind.
Take the same objective event, and people with different values will react to it in different ways emotionally.
If, for example, I am giving a presentation on a certain aspect of gardening; some people will find what I am putting forth inspiring. Others will find it boring. Yet others will see it as evidence of my hopelessly non-cosmopolitan and hence unworthy mindset.
The objective event has not changed -- but the emotional reaction in its observers has changed in accordance with the observers' respective values.
A person can experience "love as a response to values" when noting the existence of his/her highest values in the person of another.
What these values happen to be will, of course, vary. Some people hold values I would consider to be quite twisted, which will cause them to love an abuser, for example.
When "love as a response to values" occurs; it is more of a spiritual thing. At that level, it can result in admiration, friendship, etc. But when combined with physical love -- that inscrutable chemistry of attraction -- it can become part and parcel of romantic love.
In romantic love of this sort, the other person's very existence serves as confirmation of the goodness of life. In many ways, they add value and pleasure to our lives -- and make it more worthwhile ... more worth living.
In this sort of romantic love, something done for the other is not a sacrifice; because the other's wellbeing is seen to enhance our own.
In those cases where a combination of physical love and "love as a response to values" exists for both parties ... the other's mere existence is seen as sufficient justification for sex.
I should add that there is a tendency for partnerships of this type to be fairly autonomous, not particularly prone to jealousy, and not especially possessive. The participants likewise tend to be not especially superficial or materialistic.
I do not believe they are especially common; but because they DO exist ... that is sufficient justification for me to disagree with the statement that "ALL men PAY for sex in one form or another."
So that's the answer. For further discussion, though -- read on.
Now, on the other hand, I think that MOST men pay for sex in one form or another.
This is a natural consequence of the differential in the way men and women (in general, not in all cases) view the world.
In general, men have lower criteria for what constitutes a sex-worthy woman than women have of a sex-worthy man.
Because of this differential in criteria; and because when taken as a whole the quality of men and women is just as high; the female drive for higher quality partners will, in most cases, leave women unsatisfied with the men available as mates ... so very often they will feel that they have "settled."
Now, this is a FEELING, not reality. In MOST cases, when a woman ditches her husband in order to be available for a "better" man; her subsequent mates are of the same or even lower quality than the one of which she divested herself. Nevertheless, her feeling of being worthy of better than she is getting puts a negative balance in her mind.
In other words, most people (men and women alike) do not question certain of their feelings or correct them to be in conjunction with reality. So even though the quality of available men is no lower than the quality of available women; a large percentage of women will go with this feeling (called the hypergamous impulse) and will be dissatisfied with a man of the same quality as themselves because they will see their own quality as being higher than it actually is.
This feeling is augmented by girlfriends who will continually re-affirm its validity by telling a woman that "You are worth so much more than Joe," etc. Meanwhile, our dominant media culture -- along with giving men very unrealistic expectations of women -- also plays into enhancing this feeling which has its basis in hypergamy; thus creating the false impression of much better men always being ready and available.
So, in essence, a great many women feel CHEATED in their relationships. In their equation, "love as a response to values" comes up short; therefore they see the man as OWING them something more than he provides simply through his existence and commitment.
Naturally, they set about getting that payment in various ways -- including demands for various material goods and services. In this way, a great many men end up paying (quite literally) for sex.
But there is a converse male phenomenon as well.
We have a society that is obsessed with consumerism and materialism; and in which wealth -- in and of itself, no matter its source -- is seen as proof of virtue.
Many women come to believe that wealth is a man's single most important attribute; and many men will accumulate wealth as a response -- realizing that women who buy into the materialistic mindset can essentially be bought with nothing more than money.
Some men play this. And I will admit that there was a small subset of my life where I played it as well. I discovered that ostentatious displays of wealth would have a certain subset of women draped all over me and "hot, wet and waiting." So, naturally, that's what I used to bait my hook.
It didn't take long for me to be disgusted with myself and with what I was catching; however.
But many men will NOT be disgusted with the results. And they essentially pay for sex through their choice of women. After all, what you catch for fish depends on what you use for bait -- and such bait draws in very high (financial) maintenance women.
Sometimes, men of this sort will use that approach simply because they feel that their material success entitles them to whatever they want in terms of women. (Of course, some women cannot be bought; but the guys don't believe this.)
Other times, material bait may be used when the man feels his character is otherwise sub-par and not otherwise worthy of "love as a response to values."
Yet other times, it's just the easy approach. Although I dated a lot, I hated the whole deal where I had to somehow impress an extremely critical audience. An ostentatious display of wealth can, in many cases, at least get you over the first hurdle.
As David Lee Roth noted; money can't buy happiness but it can buy you a boat big enough to let you sail right up next to it.
But, either way, this tendency can create a circumstance where men are essentially paying for sex.
Executive Summary
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There is a subset of matings in which neither party is paid for sex.
Sometimes, men do not need to pay because they manifest values that result in "love as a response to values" in the woman.
And, frankly, some women cannot be bought at any material price. They will hold out for a man worthy of "love as a response to values."
However, female hypergamous impulses, male drive to wealth acquisition and a common human tendency for both take the path of least resistance combined with a hyper-materialistic culture creates a situation where a great many men -- I would say most -- are paying for sex in some way.
