We are experiencing the same thing that happened with Trump and the rest of the republicans in 2016.
The others must get serious and stop attacking each other, and go after Sanders. The difficulty is in the fact that he tells the truth about where America is today. Most Americans, including deplorables know that, which is why Trump got elected, despite the fact that he fooled them to think he can do anything about it, because only he and his clan and buddies benefitted.
Sanders’ problem is his solutions, some of which are bs, won’t pass ever, and will set America on the wrong foot. It is like listening to the gobbledygook the Greek socialists filled the air with since the late 70s, and the results of all that as the whole society bought it. Populist pressure is dangerous.