Just out of curiosity, why the fuck do you think you get to define who is a "real" Dem and that "'progressives' hate the Dems" - thus defining progressive as "not real Dems"? Who the fuck do you think you are?
"Hijack the party?" I could say the same about the DLC backed Clintons in the 90s. FDR was as different from Bill Clinton, Barack Obama or Joe Biden as Nixon was, and FDR was the most popular president EVER.
Socialists have their own party. Some people don't want to join the socialists, or the DSA. Maybe they (rightly IMHO) are pissed because they know the two major parties have rigged the system against smaller rivals.
So a bunch of people - Democrats - have decided to try to take their party back. Suck it up, buttercup. That's politics.