@ sobre mi cadaver
Because it's not the popular vote that counts; it's the electoral votes.
So like say Romney
overall got more votes--but let's say all those votes were from people in states with smaller populations (and thus less electoral votes). So even if he got millions and millions of votes and won lots of small states, he'd only get, for example, 200 electoral votes.
Then say overall fewer people voted for Obama, but those votes were from states with lots of electoral votes, like Cali and New York. So even if he got less votes overall, as long as he wins those states with high populations, even if it's by the tiniest margin, he can easily get 270+ electoral votes.
And that's the main reason people hate the electoral college; it's totally undemocratic and unrepresentative. For example, let's say 49% of people in California voted Republican, the other 51% voted Democrat. Even though it's clear that nearly half the population wants the Republican, all 55 of Cali's electoral votes would go to the Democrat.
That's why candidates freak out about Ohio, Florida, etc. They're states with lots of electoral votes, but they can very easily go for either party.
I hope any of that made sense or helped at all.
I'm terrible at explaining but I can answer any specific questions. The whole system is really, really,
really stupid, tbh.