I have some novel ideas for how fridges should work. I don't build fridges though. I have no intent to ever build a fridge. I don't want to build a multinational fridge-empire that takes on Samsung and LG and the rest.
I should be able to sell my ideas to those companies. Patents are how I can do it.
If I patent the idea and nobody does it for a few years, but then somebody picks it up, am I not entitled to something? You'd label me a patent troll, but it was my idea that I worked on for a few weeks. I'm the engineer who thought of it - I just didn't have the resources* at my disposal to bring it to market and distribute it worldwide at a cost customers would accept.
In software, this does seem a tad stupid, though. Scaling software is so trivial - who is capable of building worthwhile software but then finds that distributing it to customers is too daunting? Hardware is a totally different beast.
Patent trolling doesn't just mean patenting something you don't make. It means making patents, usually as vague as possible, with the sole intention of later suing companies that accidentally "violate" them. They never sell the patents, only sue. And they pick the courts that will treat them best, usually in Texas. It's been this way since the 90s at least.
I agree you should be able to invent things and never make them, instead selling the patents, and that right has to be defended. But when it comes to non-UI software, few ideas are novel, and almost always the entire value is in the execution. I don't know if companies ever buy software patents with the intention of using them. In Big Tech, patents are more for ammo in court in case another big corp goes after them.
So yes, if someone is sitting on software patents, chances are they're a troll. Not necessarily, but probably.