well i've rejected from yc 5 times in a row now. my project folder just grows bigger and bigger. but i guess it goes with the territory of thinking i'm an entrepreneur.
Try maybe Prosper? Or ask your friend engineers? The money at YC's levels can be found just about anywhere. The YC 'bump' with expertise, connections, etc, is likely of very high value, but zillions of people get by without it.
It sounds like your ideas may not align with YC-- maybe it's them and not you?
If you've proposed 5 times, you've got more gumption than a lot of entrepreneurs-- just keep moving.
I struggled with bouncing from ideas too long, and really there isn't one factor that makes or breaks an idea. A lot rides on the execution. So start executing to start making some new mistakes to learn from, thats what I am doing :)