If it’s short-sighted as you call it, then please educate us on when this has ever happened in the past.
Please explain how the Democratic party dominating the political landscape will make them abandon their ways and move to the left. Do you think winning elections will make them abandon their political donors? If anything, losing to Trump in 2016 should have driven the party further left but instead we got another Republican-lite candidate who barely beat Trump. The same person who lost to Clinton in the primaries previously and that is who we have as a candidate once again. “Winning” doesn’t usually make people reflect on their actions and decide they need to change.