Its because the DNC hates progressives just as much as the GOP hates liberals. The DNC self sabotages and progressives have no other viable option for party affiliation.

Trump could've been impeached for countless things in 2016/17/18, but no, the democrats only decided to try to impeach him when he started digging up dirt on their chosen front-runner lapdog.

The DNC and GOP both represent special interests first and foremost. They even share some special interests like Goldman Sachs, Citigroup, JP Morgan Chase, Lockheed Martin, Raytheon, Pfizer, Geico, UnitedHealth, MetLife, Prudential, Exxon, BP, Chevron, Marathon, Ford, GM, the list goes on.

I'm a progressive and I can clearly see that the DNC and GOP only differ in their positions on social issues like abortion and gay marriage. The progressives in the party makes the rest of the party look good, because they talk about the real issues. But when push comes to shove the DNC will ALWAYS prefer a status-quo corpo-dog liberal to a progressive who wants the government to do what its supposed to and serve the people.