Yes I know, your least-favorite idea goes here. But seriously, someone must have come up with the concept before. Like a bad get-rich-quick scheme could fall into this category, where joining the scheme makes people lose money and become more desperate, so they become more likely to do desperate things like invest more in the scheme. But it can apply to a number of other bad ideas.
Feels like there ought to be a term… it’s kind of a mix between “vicious circle”, “feedback loop”, and “echo chamber”.
There is the sunk-cost fallacy, but that is more about investments. I don’t know if it’s refers to popularity like OP wants.