Trump’s base is not big enough to bring sustained electoral success.
The Democrats’ potential base is bigger.
However, so many of them are lazy couch-dwellers who can’t be bothered to get up and go vote.
I would take a rock solid base of 45% against a wishy-washy majority of 51% any day of the week. In the mid-terms, it’s all about who shows up to the polls, and in the general election, if your base is completely with you, that gives you a lot of leeway to appeal directly to the middle. Especially if the Democrats’ base is smaller, which I think it is, at least where it matters (swing districts/states).