I would say if you know what you are getting into while you are doing it, if you talk to the other person you can get some of the power back.
In all honesty, I don’t know what I would do if a celebrity shows me some attention. I probably would get at least flattered. And then I would wonder if he/she is getting a stroke. But seriously. If I get someone I admire to give me his/her attention and maybe I want to get intimate with him/her, if I clarify the boundaries of the relationship before hand, what are my expectations, then maybe I can have the sex, enjoy it, and feel good afterwards.
I think what this dude did left you with a bad mouth flavor because he used you. Would the expectation had been from the beginning “hey, are you ok with having sex and calling it a day?” You would have been able to make an informed decision and then decide “is this something I want?” If the answer is yes, you enjoy a good time with someone you admire and all good. If not, you preserve yourself.
Anyway, thank you for your vulnerability and sharing your story.
Pablo