That ideas are expensive, it's implementations that are valuable.
The smaller and narrower the idea, the easier it is to implement. Just keep whittling away more and more out of the idea and just boil it down to its core essence, so that you shed as much of the expense of your idea as possible. This makes it faster to implement, and once you've implemented it funding is easier (plus, you won't have time to work on code once you start looking for investors, they're even more expensive, and the more ideas you have to explain to them the more expensive they get).
So yeah, ideas are expensive. Don't worry, nobody will steal them, so share it with the world, if they tell you it's a bad idea, thank them, they just saved you a lot of time and money.
The smaller and narrower the idea, the easier it is to implement. Just keep whittling away more and more out of the idea and just boil it down to its core essence, so that you shed as much of the expense of your idea as possible. This makes it faster to implement, and once you've implemented it funding is easier (plus, you won't have time to work on code once you start looking for investors, they're even more expensive, and the more ideas you have to explain to them the more expensive they get).
So yeah, ideas are expensive. Don't worry, nobody will steal them, so share it with the world, if they tell you it's a bad idea, thank them, they just saved you a lot of time and money.