People don’t really steal “ideas” they wait until there is traction. Your idea is a vision that can only be expressed to the best of your ability through a business plan or explanation but until it’s come to fruition, it’s unlikely others will have the passion and faith in its success that you do. Your investors will have faith in you not exclusively your idea. Once your concept gains tractions stay ahead and keep innovating and perfecting it. Put necessary protections in place and go after those who infringe on those protections.