[Sohcahtoa82]

There's a key difference though.

If you invent a better system for making ball bearings and patent it, you could bring your system to existing manufacturers and say "I've invented a better system, would you like to license my patent and start using it to bring your costs down and productivity up?" That's fine and most people would be on board.

But a patent troll is different. They're entirely reactive. They wait for someone else to start doing something that is vaguely similar to what you patented, and then they pounce. The troll threatens legal action if they don't license the patent instead.

What patent trolls do is effectively extortion.