First of all, disapproval NOW is irrelevant. He got 49.8% in the last election, higher than his current approval rating. Someone having regrets because they made a bad choice doesn't negate that they made a bad choice in the first place. WE (meaning many of the posters on this board) had access to the same information in previous elections that other people did, and still recognized that Trump would be a disaster.
Secondly, even a voter didn't particularly want Trump to be president, how many people simply DID NOT VOTE? Or spoiled their ballot? Or voted 3rd party? Granted, they didn't actually support Trump in the previous election, but they looked at the 2 candidates, one of whom was a convicted felon who said he would "make America a dictatorship on day 1", and the other was a politician with no criminal convictions, who happened to be female, and said "I can't decide who to vote for"? If a person cannot make up your mind between fascism and democracy, they deserve part of the blame.
Now granted, not every American is to blame. Harris did get ~75 million votes in the 2024 election, so their are absolved. But there were ~245 million eligible voters. That means that 170 million Americans did not think Trump was bad enough to actually vote against. (They supported Trump, did not vote, spoiled ballot, etc.). Less than 1/3rd of Americans actually opposed Trump in a way that it mattered. If 2/3rds of the population are OK with fascism, you have a problem.