What caused him to sell his soul to the Left?
It became easier for him to pursue possible tenure in the White House once he started aligning his views with the Powers-That-Be within the Democrat Party. Once he started down that path, he lost his soul.
Bernie Sanders has thrived by abandoning whatever made him authentic and becoming a robot reciting dogma in a voice borrowed from Larry David. Hillary Clinton never had a soul, but Bernie Sanders sold his in the hopes of beating her. And he got a bad deal on his soul because he can’t even seem to do that.That Bernie is long gone. He was once for securing our borders because without them it “says essentially there is no United States” and “would make everybody in America poorer.” Now he's taken just the opposite position because it fits the narrative he needs agree with in order to get any support from the Leftist elites.
Originally Bernie Sanders was an independent who held unconventional views on some issues and wasn’t tied down to the Democratic Party and its widely loathed identity politics. Instead he could just do his old time Wall Street Socialist shtick and score populist points with angry voters without having to pander to every group and cause in the progressive politically correct spectrum of stupidity.
By the time all of this is over Bernie will have given up on every belief and position he's ever held and done so just to have a shot at the Oval Office.
Not that I miss the 'old' Bernie. I don't. In many ways the old Bernie was worse than the “new and improved” Bernie, being someone who wanted to burn down capitalism and replace it with a system everyone who paid any attention to history knew to be nothing more than smoke and mirrors, one that always devolved into tyranny, misery, and poverty.
The new Bernie wants to tax the bejeezus out of everyone (to the tune of $15 trillion) and have Big Brother government give everyone “Free Shit”. However, the outcome of this would be the same as what the old Bernie advocated. It would just be repackaged.
And to think that Bernie sold his soul for this and all he'll get out of it at the end is a “Feel The Bern” tee-shirt.