Ideas are worthless. And it would be totally legal for them to steal them. Maybe you are confusing patents, copyrights and other intellectual property.

An “idea” has no legal protections. And you can be pretty sure you are not the first one to have any given idea too. And if anyone can steal a single “idea” and replicate your business, it is a very bad business. What you need is lots more including many things like a business model, target market, product/service and hundreds of ideas.

Companies need a team, plan and many protectable ideas. These are protectable intellectual property when kept as trade secrets, patents and copyrights. Almost every company should have some of these and contracts with employees to prevent them from taking them.

Investors do not sign non-competes or non-disclosures because they need to meet too many people.

Frankly, if your “idea” is all you have, you should not be talking to investors as you are...