1, we are not a democracy, we are a constitutionally-limited federal republic.
2, at no time in Mr. Buttigieg's lifetime has the Electoral College "overruled the will of the people."
2a, neither Al Gore in 2000 nor Hillary Clinton in 2016 achieved a majority of the popular vote. No one did in either year, nor did, for that matter, Bill Clinton in 1992 or 1996. It is ludicrous to suggest that a plurality of people packed into small urban islands represents "the will of the people."
2b, considering the Constitution explicitly requires an electoral vote majority, if we were to extend the same principle to the national popular vote, all four of the elections I mentioned would have gone to Congress for the runoff. Of those, the two latter ones would have still been one by Bush and Trump, while in 1996, Clinton would've been voted out by the Gingrich-led House and Bob Dole would be President. It's hard to say what would've happened in 1992 given Perot's following, though... let's just assume Clinton would've received the Democratic Congress's vote.
"Majority rule" only works when you actually have a majority—and even then, it has dangerous drawbacks that need to be checked. What the Democrats want is plurality rule, or even minority rule.