Many patent trolls are really trolls. But being a "non-practicing entity" doesn't make you bad. For instance an academic research group might invent a technology that is useful in making microchips but only a few companies are capable of benefiting from that so that research group/Uni is a "non-practicing entity" that can license the tech fairly to one of those companies.
You often see things like this garden hose
https://pockethose.com/pages/copper-head?variant=44089443483...
that are marketed under the "as seen on TV" brand. The company behind that licenses patents from inventors and they feel like they can invest in marketing and development because the patent holds back cheap competition.
In the case of that hose, competitors figured out other ways to make a hose that does something similar and you see a common scenario -- that page boasts about all the improvements they've made in the product, starting out with one patent helps them lead in a competitive market in which they've gotten many more patents to improve their product.