Outside of software patents which I don't think should exist, I don't see a problem with buying and sitting on a patent for something truly innovative. The original creator was rewarded, the knowledge becomes public, and the buyer can sit on it as they like for ~15 years. If it's a profitable concept they are wasting money by not developing it.
The problem comes when courts uphold illegitimate patents. Fortunately there are companies who will stand up to this, such as Newegg and Cloudflare.
How so? Any competition is unable to proceed because of the patent, and all you need to do is put some money towards renewing it every X years. Now, if there was competition, of course you would lose out from developing it. But there can be no competition because of the patent, so at the time you hold it nobody can develop the patent.
You're Codake, a company that sells chemical photography materials.
Some person invents digital photography, you find out and buy the patent from them for 500K.
Digital photography would hurt your profits so you just sit on it for the 15 years, maybe start designing some products around it in the last 3 years of the patent to be ready for when it expires.
You made more money and society lost out for 15 years, all because the inventor probably wasn't used to seeing large checks and didn't shop around when the largest photography company offered them more money than they ever saw in their life.
Even the inventor got screwed, by selling the patent they got a nice house even though it was probably worth hundreds of millions.
I don't have a solution, just a vague feeling that in 2021 15 years seems like a very long time (for software, at least.)
Design and practice are two different things. Patents, in practice, are hopelessly broken when you can buy a fairly general patent from someone else, sit on it without ever actually using it, and then sue someone else who had no way of knowing the patent even existed. And that's not just in software.