The problem is the DNC really doesn't care about winning. They still get their lobbying money and donations whether they're in the Whitehouse or not. Arguably they might get more when someone like Trump is in charge, giving them the perfect person to point at and be outraged by, continually asking for donations to stop them but once in power doing the bare minimum to undo and stop Republicans. Republicans on the other hand have a lot of people who are motivated by what they want to accomplish and want to win and use whatever power they have to get what they want.