My opinion?
Republicans underestimate democrats. Liberal democrats aren't dumb. They just hold different beliefs than we do. Some of the hardest working and smartest people I know are liberal democrats. True believers. Zealots. They were pissed when Clinton's '94 ban didn't actually ban the things they wanted gone. They were pissed when that law sunset. They were pissed when Trump "stole" the office from Hillary then nominated conservatives to the Supreme Court. So they huddled up and analyzed their failures, figured out where they needed to improve, and came up with a plan.
Conservative republicans keep getting caught flat footed. And when they have the advantage, they both fail to use it effectively, and take actions that please far right wing conservatives but piss off everybody else, which causes them to get unelected.
The rest of us are actually libertarians, not far right wing conservative republicans. We want to live our lives as we see fit, not run everyone else's lives. And as long as we're being largely left alone, we just go about our business. So we don't fight until cornered.