Dems don't always win elections. They lose they presidency, sometimes in a landslide! They lose the House. They lose the Senate. Sometimes they win these things, too!
For some reason (we can guess what it is) there is a loss narrative focused on 1972 and 1994 in particular, though 2010 somewhat similarly. Those are the elections Dems lost!!! Of course they lost plenty of other elections, also, too. But, really, we need to learn the lessons of 1972.