i don't think it's as simple as 'covering bases' to be going up against a well-resourced party structure on its own terms and expecting change. to me that is an unrealistic expectation.
i'd rather see challengers running under a different party, i just have zero confidence in the democrats at this point.
i still vote because it's convenient, i even vote in primaries and municipal. i usually just write in bullshit for all the races that are unopposed or where the democrat also sucks ass. we don't have a national popular vote so my vote for president is essentially meaningless.