I had the old "got this great product I've developed, but can't afford a website, could you do it in exchange for a percentage of profits?"
Look, it's your product, I have had no say in its development, or quality or how you market it etc. I do websites and the website will do exactly what you want it to do. I couldn't give a fuck wether you sell one or a million. It's not my risk. Pay me for a site and I'll do it.

It's a sad because most devs who are trying to make an entrepreneurial living are forced into this percentage of profit shit. It happened to me, but the guy had a good concept that he was ruining with his unrealistic MVP. Who the hell wants to invest time working on something they don't believe in that their only pay is potential crap profit?

Just say no, but it pays to listen. If the person is credible,!idea is good and situation is right then maybe some risk for a big payoff is appropriate. Did one early in my career that worked well.

@Jumpshot44 I did just say No, that's my private rant. He wanted to start selling it when it was way underdeveloped and had one of those ridiculous Kai Krause interfaces that defies logic and reason. It was a Windows program for creating music based on relationships, a bit like a colour wheel for music. My advice was to polish it up and sell the concept to a large organisation with deep pockets. He wasn't competent enough to pull it off on his own.