You're right, this will be a fast way to get people to stop telling you their ideas. But if you're trying to shut people up then you've missed the OP's point.
You can easily make normal people feel like their idea is worthless and you have mountains of business acumen that, obviously, they must lack. Do this enough times and what you'll find, just like you'd hoped, people stop telling you their ideas.
I'd argue that every time you do this you are shutting down opportunities to collaboratively create ideas that would probably work. Part of being "lucky" is increasing your exposure to failures [1].
When someone approaches you with an idea, you've certainly got a better feel for what will "work" more than you're average person. Consider taking the time to give feedback, help shape it, brainstorm with it. You might find that between the two of you what you create is bigger than what either one could come up with individually.
This applies in all areas of personal relationships, not just iPhone games.
[1] "To increase your chance of success, double your failure rate" - attributed to Tom Watson
My point isn't to "shut people up". If it was, that's what I would have written.
My point is to get people out of the mindset of "if I could someone ELSE to do all of the hard work, I'd be a gazillionaire."
My approach is to tell YOU how to seize the opportunity and get your idea rolling; I'm far too busy to do all of the work for you so you can retire rich, but I will gladly point you in a great direction and lay out your next steps. The reality is that you won't do it once you realize that YOU will actually have to do the grunt work.
You can easily make normal people feel like their idea is worthless and you have mountains of business acumen that, obviously, they must lack. Do this enough times and what you'll find, just like you'd hoped, people stop telling you their ideas.
I'd argue that every time you do this you are shutting down opportunities to collaboratively create ideas that would probably work. Part of being "lucky" is increasing your exposure to failures [1].
When someone approaches you with an idea, you've certainly got a better feel for what will "work" more than you're average person. Consider taking the time to give feedback, help shape it, brainstorm with it. You might find that between the two of you what you create is bigger than what either one could come up with individually.
This applies in all areas of personal relationships, not just iPhone games.
[1] "To increase your chance of success, double your failure rate" - attributed to Tom Watson