Maybe not trolls, but patent hoarders, and the only way they make money is by suing others.
Not saying they aren't justified since they own the patent. It's just a slimy business model.
The fact that it's an unethical and "slimy" business model basically means they're not justified. If there was any real justice, the patent system would be trashed and copyright law would be seriously revised. Both systems have, thanks to capitalist lobbying, turned from their core missions so dramatically to become systems to accomplish exactly the opposite of their core missions. They now stifle invention and only protect the interests of huge wealthy non-human, non-individual, corporate entities. Thank you, corporate personhood.