It's really misleading to state
Clinton's popular vote win came entirely from California. Yes, Clinton won by a larger margin in California than any other state. But if we removed one state from Trump's total, Texas, he wouldn't have won the EC. There's also the fact that Hillary won almost 50% of the votes in the REST of the states. Even many of states Trump won, he won with a tiny majority making it easier for a few million votes to put Hillary over the top.
California is the largest state by far with one in every 8 Americans living there, twice as many as live in Florida and considerably more than in Texas. That said, California is 12% of the population so if the rest of the nation voted against a candidate by a large margin, California could not override it by itself. As much as the right likes to demonize California it has nearly twice the GDP of Texas and if you removed California from the USA GDP would drop below that of the European union.
The US constitution was written when there were 13 states and 4 million people in the entire country. Population disparities between states were relatively small. Human population has ballooned in general but especially in the united states with immigration and territorial expansion. Population has also become tremendously more concentrated than the agrarian society that was present in 1789. This means the population disparities have become far more extreme than the founders probably could have ever imagined. US population is now around 350 million people, about 85 times what it was in 1789.
We need to recognize how much things have changed and for our government to function best, change to deal with the problems caused by the march of history.