I too have lots of good ideas that I have gotten funded other more sane and normal ways. LOL
Guarantees of success are only really present when there's history behind a business, and even then historical data and predictive analysis can only carry you so far, and sometimes borders on gambler's fallacy. Someone had to take that risk to get there.
I'm taking a risk selling this idea without building a business around it that I could be throwing away a huge opportunity (like how Bill Gates bought DOS for like 50k back in the day), but given my circumstances it seems the better option.
Tough for you to generalize without enough information to fully evaluate though I understand, and so many factors hinge on success - it's true.
The way I'd probably want to do it is have an NDA, then partial disclosure, then if the concept seems exciting enough we escrow exchange btc for rights signed off and call it a day. It's not like I'd expect someone to just blindly pass that much my way without having a chance to fully review the situation - that'd be just asinine.