There are some Democrats who remain registered that way, but vote for Republicans. It’s a family thing.
George Putnam in Los Angeles was that way. He railed on the Democrats and Leftists non-stop, but he remained a Democrat out of loyalty to the old days.
Frankly, I could never have become a Democrat at any point in history I can think of.
There was a time when I would split a ticket, voting for a Republican for president and a Democrat for the Senate but that was long ago. I am at the point now that I don’t want to vote for most Republicans and there is no way on Earth I vote for another Democrat.