I obviously can't take responsibility for every developer in the world, but most of them I know think in a similar fashion that me. :)

I think you need to consider your advantages and the fact that you are already ahead with your MVP. There is no need to disclose everything. Besides, even if your MVP is working as it is supposed to, there are miles till you actually make in in the market. Been there, done that.

Think about this: if the person has the skills / connections / opportunity to make execute this idea better than you, you should consider him / her a partner in the project.