Actually, you still have a bunch of conservative people there who, in order to have the best shot at eliminating the worst candidates, are registered as Democrats. They've no intention of changing their registration status - they know exactly what they're doing.
In some places, "Operation Chaos" has been going on for decades.
You described my neighbor. He has been a registered democrat his whole life. He has never voted for a democrat for president though. When he was young if you were not a democrat you had no say so in the political process. The democratic primary was the only vote that mattered.