They had to jump through some hoops to make it into the debate stage for the next debate, and I’m guessing some of these people didn’t meet the requirements.
Some of them I assume did some polling, as others have mentioned above, and saw the writing on the wall that they can’t win. In fact, 4 years ago that’s what Bloomberg cites for not running as an independent, he did some polling and analysis and winning was seemingly impossible. Too bad he didn’t try.
Some of the dropouts never thought they had a chance, but wanted a stage to get their ideas and message out to try to have some influence, but I assume by this point are being pressured to stop diverting attention and money.
Everyone who has dropped out I’m fine with them dropping out.