I've met lots of friends on fetlife, and for that I'm grateful. In Chicago however, the dynamic is very different. The kink scene here is pretty heteronormative on the surface, and there are far more male dominant/female submissive couples than vice-versa (this is concerning lifestyle kink, not p4p kink).
I've been kinky-identified for over 10 years, and fetlife was instrumental in my education on how to do things safely and sanely. I found lots of educational classes and resources via the website, and I've had the pleasure of meeting lots of educators and taking lots of classes that have honed my skills. Personally, that's what fetlife is great for; personal growth and expansion of kink-based knowledge.
Fetlife is not a venue, in my opinion, for offering professional services. People aren't there looking for professional services, they're there looking for realtime lifestyle playmates and partners.
Depending on your locale, backpage is often one of the best places to advertise pro domme services, but you have to be aware of your audience when you're offering pro domme services; clients of professional dominas are far different than clients of escorts/providers. Having started as a pro domme and currently being a provider who specializes in kink, the difference definitely of note. There are also lots of national/international advertising websites for pro dommes. They're honestly not too difficult to find via a google search.
The issue with pro dommes being in-demand and "insta dommes" looking to cash in is the clientele difference i mentioned above. It's also why providers like me sometimes get a bad rap, especially from men seeking a traditional bdsm experience. Lucky for me, I've got reviews documenting both types of sessions