If you look at the records of issued patents and which ones are owned by known "trolls," a very small minority of them come from this approach. Writing patents

If you look at the records of issued patents and which ones are owned by known "trolls," a very small minority of them come from this approach. Writing patents to anticipate future inventions is risky and expensive, and most of those patents will be worthless because a non-expert can't anticipate the technical direction of a field very well. Buying failed startups is cheaper and easier, and a lot less uncertain.