Uber, Airbnb and Theranos come to mind first. As much as I want to see the daily fantasy sports put out of business, they at least had the foresight to punch a legal hole in the system to try to create a business (and not to mention they seem to be in the death throes anyhow).
It bothers me that investors seem to be so nonchalant about investing in a business that is in very questionable legal circumstances. I don't really know how to solve it, but it feels like investors do their due diligence (I hope!), but figure that the legal system is slow so there's a good chance that they can exit before any legal ramifications kick in.