Everyone's tastes may differ, but we all look for providers that appeal to us and turn us on. For some it's a certain ethnicity, some it's hair color, some it's services provided, some it's bra size, etc.
I hobby because I don't have the time or patience to go bar hopping to try and find the one I want, hope she's not BSC, hope she's actually interested in having a one night stand instead of just taking advantage of me for free drinks, etc, and I definitely am not going to troll M4W ads or god forbid Tinder.
I hobby because I have a high libido, I'd rather solve it with a real woman than porn, and hobbying allows me to pick exactly what I want, try a lot of new options, explore fantasies, know what to expect, have guaranteed results without a whole lot of time wasted on fluff, and at the end of it clean cut ties without any emotional attachment. All of that comes at a price I can accept, so it all works out!