Trump appeals to the populist crowd because of his celebrity status. Just another carpetbagging drunk uncle eejit would not work. The truly weezilly folks need proper cover to work their magic.
There is more to it than that. Trump is very good at finding people who feel, rightly or wrongly, disenfranchised or have a victim mentality and panders to them.
1. Trump finds unsolvable US issues other politicians avoid - like the Southern Border or the massive problems with what is now called the Rust Belt and promises simple solutions to fix them.
In reality these are complex issues and Trump's home-spun easy solutions will invariably fail, but from the voters perspective Trump is at least paying attention and promising to try.
(the likely "solution" to the rust belt is the cheap properties will be bought up by WFH hipster IT types who will renovate and put in solar and starlink and the whole area will be gentrified eventually, but this is not what the current locals would see as a desirable solution)
2. He is good at finding groups feared or disliked by a large number of voters and proceeding to persecute them. the impossible wall project and the banning of whole countries as Islamist are good examples.
3. He is also good at finding groups that have an almost narcissistic belief that what they hold to be true should be forced onto everyone else and promising to force their unpopular views on everyone. Examples here include Evangelical Christians and the neonazi White Supremacist militias.