There is no such thing as a popular presidential vote though. Using a baseball analogy, scoring more runs in a series doesn't matter, winning more games does. So you build your strategy with the idea in mind that if you're going to lose California anyway, lose it big and use those resources elsewhere.
Also of note (and just as relevant), Republicans won the Popular vote for Congress by over 3 million.[1]
That less people show up to vote in midterm elections, those that do are usually motivated by opposition to the ruling power, and possibly that the less people allowed to vote legally is an advantage for Republicans.
Also historically the last mid terms should have given massive gains in both houses instead of the extremely slim majority in a single house.
Not really anything in a first past the post voting system where lots of people vote simply because they don't need to because their party will win the state already.
Sort of contradicts your original point though. But at this point we're entering Reddit-level discussion so there isn't much reason to go down that rabbit hole.
