Holmes was a family friend of the Drapers, and his investment was a token amount. I doubt whether he did ANY due dili on that one, and find it hard to hold that against him.
This is a bigger problem than one company. This is that funding has been divested from basic technical due diligence. It's one thing to fund a company trying to make a new form of aircraft and another to fund one that makes a pill that will allow you to fly.