Video games are designed to make you hooked and extract as much as they can from you. You are slaves on the world they created, wasting your consciousness away on a virtual world. And the grinding games are the absolute worst, its just the same gameplay over and over.
It depends on what game you chose. "Free-to-play" games tend to have much micro-transactions that they really are pay-to-win. This is an issue in the gaming industry now where you already paid to own the game but it still got microtransactions in it.
As for grinding games, if it's popular enough, you can earn money out of it by selling stuff you've farmed.