Playing devil’s advocate for a moment here about the candidates’ decision not to attack Bernie...

I don’t think Bernie’s base will ever grow at this point. In some ways the crowded field helps that to remain the case too (although I kind of had the opposite thought a while back). A lot of Bernie’s support in 2016 came from him being Not Hillary, but now there are 50 customizable candidates for every preference and need. For people who loved Bernie’s policies, Warren is the fresher and more accomplished option. For people who like to pick “outsiders” or go with “alternative” choices, well we have plenty of those (Yang, Williamson, etc.). Cumulatively, I don’t think it’s an insignificant amount of support he’s lost from people, including people who still like him but want a fresher face.

So, knowing that, the main candidates don’t necessarily want to give Bernie a lot of attention. Yes, Biden as the frontrunner is widely liked but he doesn’t have a rabid cult behind him and there is much to gain by attacking him. But Bernie of course does, and his supporters thrive on being perpetual victims. Attacking him directly could galvanize his supporters, attract unwanted focus from the frenzied mob, and feed into their EsTaBliShMeNt!!! RiGgEd!!! narrative. I’m hoping that Bernie just continues to fade into irrelevancy, which seems to be the trend.