By modern standards it's huge. Everyone runs data-driven campaigns now, which is to say that they basically ignore all but the swing states, and Trump won all of the swing states.

Which is the same reason that for a Republican a 1.6% popular vote margin is massive. California isn't even close to a swing state so a Republican could flip 2M more votes there over what Trump got in 2016 and still lose the state, even though that by itself would increase their national popular vote margin by more than 2%. Trump got 1.5M more votes in California in 2024 than in 2016 and still lost the state by more than 3M votes. So Republican candidates for President ignore the entire West Coast and the Northeast -- huge population areas -- because losing there by 48 to 52 gains them nothing over losing by 30 to 70.

Democrats do the same thing in Texas and most of the South, but the blue states are bluer than the red states are red, so Republicans come into the median Presidential election with a deficit in the national popular vote and often lose the popular vote even when they win the electoral college, e.g. when Trump won in 2016 he lost the popular vote by more than 2%.

Democrats often fancy the idea of switching from the electoral college to a national popular vote thinking they would win more often, but it would really just change how both parties campaign. Republicans would start campaigning in blue states and vice versa but the safe blue states have more prospective votes for Republicans to flip. And under the existing system, any national popular vote win for a Republican is a landslide.

The better argument that people don't really like Trump that much is that he won so big mainly because the Democrats picked a weak candidate to run against him and they should have had an actual primary and picked someone better.