In my experience, you need to prove that you spent enough money (say in the order of 100k$). Spent, not just invested -- but the investment can be "just" that 100k$.
A lot depends on the embassy. Some seem to have unofficial investment amounts that exceed this. IIRC, anecdotally, the London embassy has a minimum investment requirement of $200k for E-2 which may have risen since I last looked.