I played under one. He kept players in his games because he did not treat all the players that way. He had a couple of his old crew best friends who were the heroes of his campaigns, then he would invite 2-4 more players to fill out the table. He always has a game because of his two good friends who are untouchable, but the other players are targeted for death and no matter their "choice" it will end in the same result of them failing or being made to look stupid "in the name of story". It took me a while to realize what was going on because the GM was not doing the to all of the players and was able to rationalize each individual moment. In a particularly bad session where the GM was going too far telling me how I had to play my character I realized... I was playing an NPC. My character was not there to be my player character with my player agency but to support his the story of his real friends and provide roleplay so the GM had less work. The reason he killed my characters was because I was not playing "his NPC" the way he wanted me to. It was that realization that suddenly put context to all the problems I had at that table and the large number of them I had that his old friends. Suddenly all those problems made since when I couldn't understand the issues before. Realizing that I quit and promised myself never to play under that GM again.