My advice is to first become an expert in the field that the idea is in. Once you do, you might see an obvious argument against your idea, and if not, you’ll have a better chance of developing your idea to fruition, and also have the language to describe the idea in a way that other experts will take it seriously.
If after you become an expert, you still don’t see an obvious argument against your idea, post it to some public forum where other experts hang out, to see if someone else can see an obvious argument against it. (At that point your idea shouldn’t be so wrong that someone will laugh at it, and if someone does steal it at least you have proof that you came up with it first.)
If nobody else can see an obvious argument against your idea, then try to develop the idea further and further until it falls apart.
My advice is to first become an expert in the field that the idea is in. Once you do, you might see an obvious argument against your idea, and if not, you’ll have a better chance of developing your idea to fruition, and also have the language to describe the idea in a way that other experts will take it seriously.
If after you become an expert, you still don’t see an obvious argument against your idea, post it to some public forum where other experts hang out, to see if someone else can see an obvious argument against it. (At that point your idea shouldn’t be so wrong that someone will laugh at it, and if someone does steal it at least you have proof that you came up with it first.)
If nobody else can see an obvious argument against your idea, then try to develop the idea further and further until it falls apart.