This is an interesting assertion. As someone who has had ideas stolen, I wonder what research has actually been done to support this claim? It seems to me that the problem lies with the fact that most people with ideas and few funds have a difficult time actually going after someone who does behave unethically and gets away with it. So an ethical investor should understand this and be willing to do his or her pro forma due diligence just as he or she would expect the management team to do theirs. Would you invest in a company that had not asked its members to sign an NDA or non-compete clause? Highly unlikely. So I advise my business students, on either side of the table, to just do it. Makes everyone feel better even if they don't get enforced often, or often enough.