If the idea is solid and fleshed out (bonus: On paper) and not just a one-liner like "it's My____ but for Chilean expats in Micronesia", then they deserve more than just "build it myself and then Winklevoss them".
Maybe they can do balsamiq mocks of the interface, can run the incorporation/LLC paperwork gauntlet (if it's more than just an app), do beta testing, buy devices to test on, pay you a "solidarity" stipend, research, marketing, wrangle a QA or translation staff on Mechanical Turk.
No one ever has "zero ability to execute". It can't just be about the coding.
How are they "less than zero" if they gave you an idea that a) you would've never thought of yourself in any amount of brainstorming or b) was so insanely great that you jumped at the chance to actually do it.
Would people who are passionate enough to really think things through with their idea contribute less than zero? I'm not talking about the fictional coked-out, fast talking movie exec with logline "business plans" that want 60% + a seat on the board. If you're talking with that kind of person, then of course you don't take it on.
It's really easy to contribute negatively to a project. On the business end, I've worked with people who changed priority/direction/feature-sets so frequently that they actually made things worse; the project would have been better without them, hence a negative contribution.
On the technical side, have you never worked with a programmer that insisted on introducing his favorite framework/language, or declared that the "current code sucks, it needs to be re-written"? That's potentially a negative contribution. Hell I've even been that guy. It's not only possible, it's common.
In my experience, rewriting code almost always ends up a net positive.
I think the negative influence is usually more in line of those who resist change such that so much cruft accumulates, that it truly becomes too dangerous to change anything.
Sure, but if the person actually had the idea that created the entire venture, it can't really be negative unless their influence runs it to the ground and puts the company in debt, I guess.
The vast majority of people who are aware of a single great idea probably either heard it from some other party or just got incredibly lucky. People who can consistently come up with good ideas are a tiny minority compared to the amount of people who are aware of a good idea.
Yes, in a perfect world they could contribute those things but the chances of that being so are just too unlikely. If they could afford/justify any financial contribution, they'd probably just pay you to build it for them and have complete ownership.
If you have a bit of a track record, you will get people looking to partner with you and coast on your experience - in 99% of cases, it won't be enough to carry their part of the bargain or even be anything but a distraction or pressure.
Then there's the issue of feeling like you must persist with an idea you've lost faith in because they're still keen. Maybe you have countless other ideas to push that should be a greater priority, while this is their only bun in the oven.
Maybe they can do balsamiq mocks of the interface, can run the incorporation/LLC paperwork gauntlet (if it's more than just an app), do beta testing, buy devices to test on, pay you a "solidarity" stipend, research, marketing, wrangle a QA or translation staff on Mechanical Turk.
No one ever has "zero ability to execute". It can't just be about the coding.