His tally represented c. 33% of registered voters, c. 25% of eligible voters, and c. 49% of the votes actually cast. The largest single block of registered voters was actually people (idiots) that couldn't be bothered to vote. It's a quirk of our rather antiquated system that a person can be elected president without anywhere near a majority. Most other modern democratic nations have systems that require a majority, usually via a runoff election between the two top vote getters.

That costs money and takes time, of course. And in the US system, there will be only two candidates with a realistic chance of victory. The two major parties, loathsome though they may be, are essentially unchallenged. But the gap between Trump and Harris was smaller than the number of votes for other candidates, so a runoff might have produced a different result. We have no realistic way of knowing.