That’s literally not a thing. Once something is publicly disclosed it can’t be patented (unless it is by the discloser during the one year grace period). You can’t take someone else’s invention and patent it. If someone does you can invalidate their patent without even a lawyer. If you want something you invent to be free for everyone the best thing you can do is get it out into the world and not patent it.
You're not supposed to. That doesn't mean it doesn't happen.
Nobody wants to spend the court costs to get a patent troll stripped of their bad patent. And for a patent troll you're going to need a lawyer, they're going to fight tooth and nail to keep it since that's their source of income.
Once again, this is not true. They do what is called a prior art search as part of issuing a patent. They look worldwide for anything that could be considered your invention before your filing date before issuing a patent. Even after a patent is issued, if prior art is presented to the patent office they can rescind the patent. It’s a form and like $100. You don’t need a lawyer to bring prior art to the patent office’s attention. The legal battle will be between the patent office and the patent troll if they are trying to contest the prior art.
What? There was no polio vaccine patent. The inventor literally did exactly what I suggested. He made his work freely available so that it could not be patented. Volvo made a business decision to make their patent freely usable and we are still talking about it. Their brand has been permanently associated with safety because of it.
Notice how they tried to patent it “to prevent companies from making unlicensed, low-quality versions of the vaccine. There is no sign that the foundation intended to profit from a patent on the polio vaccine.”