Easy gig compared to what? Certainly there are more difficult jobs, but I'd hardly think it's easy. This feels like the same mentality as people who say it's easy to be a streamer, or the way people would say it's easy to be a YouTuber a decade ago. I think there is a lot more work that goes into it than you suspect.
Especially if you're saying it's "for women only" implying it's just male gaze propping them up. If you really believe that, wouldn't that make it more difficult? Wouldn't that imply women only have a few years to make money while they're in their "prime"? Wouldn't that imply they need to have a strict diet and workout routine to maintain their figure?
I think it's more work than you'd think. Plus, much like people pursuing other forms of content creation, there are a few people making a ton of money and a whole lot making little to nothing.
Also, what do you mean by "simple gender dynamics"?
Selling your body to any man with money does not seem easy at all to me. Or do you think all women in prostitutuon, and men for that matter, are there because they like it?