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.
I don’t know if the ‘wanting is better than having’ trope is the best fit but it’s a decent fit and kind of caters to the social aspect of what you’re describing. You know, some shiny trendy new thing and everyone’s chasing after it and as people get it they’re sorely disappointed, but it doesn’t dissuade others one bit (sometimes the reaction from the initial acquirers causes even more appeal to those who don’t have it) , until everyone is all disappointed. And then the moral of the story plays out in the resolution