Here's the setup: You meet a person who wants to starts a venture...but they want to keep 100% ownership. They want you to help them by dedicated time, ideas, and other resources to start and grow the venture...but they want to retain one hundred percent ownership. I find that to be incredibly stupid.
Who in their right mind is going to put in that time and effort knowing they won't benefit in the upside? The person asking for help with no equity in return should put a disclosure to the effect like; I'm not rational and should be treated as such. That way if you respond you know you're perfect for each other; both irrational!
I once heard a venture capitalist say; a hundred of shit is still shit. I see his point. Having complete ownership of nothing is still nothing. The smart people find a way to share equity with other smart people so they all can build a great venture and prosper while the idiots hoard every ounce of equity to the detriment of their venture.
I'm not saying you should give out equity without careful analysis but hoarding for the sake of complete control is completely idiotic.
The takeaway: 100% of nothing is still nothing. 50% of a successful company is still a successful company.