It is of course understandable how you feel.
But leaving that aside, I don't seem to find it too hard to at least empathise why people may want to vote for Trump (beyond them all being seen as racists and idiots) . The attitude of being appalled at and ridiculing Trump supporters is also in part why there is such a highly charged and polarised election.
There are plenty of reasons why Kamala can be viewed as a terrible candidate (most Dem voters would agree to this themselves six months ago).
Let's say for the sake of argument but what you say about Harris is true - she laughs a lot and lack substance. Then compare what we know about Trump, that he lies continually, is racist and misogynist, admires dictators from Hitler to Putin, encouraged his supporters to overthrow the constitution and is threatening to use the army against his opponents.
Apparently you (and Sonoma Blue) don't seem to see this as a problem compared to 'laughing Kamala'. But the no substance stuff is nonsense. Whatever criticisms one might have of the limitations her (extensive) policy programme, she is an extremely intelligent and able woman who demolished Trump in the debate without breaking sweat.
Biden seems to have had a lot more substance but he is past it now
Genuinely interested in what sort of US Trump voters want to see.