The answer to why Trump supporters think that he is not corrupt is the same as the reason that despite Trump going onto national television and proclaiming that he would proudly shut down the government over funding for a wall only to have the majority of such people blame the Democrats anyway. It's intense tribalism absent other principles. Anything Trump does will be OK to his base - anything.
Or maybe a Trump supporter reading these words can tell us what would turn you against Trump, and cause you to see him as morally or intellectually unfit to be the America president?
If any legitimate charges are ever brought against Donald Trump then he will be dealt with accordingly. But until that time he, like every American citizen, deserves the right to a fair trial in a court of law, not a public lynching
These are parallel processes running concurrently. He's dealing with both the law and the court of public opinion. The public has no duty to reserve judgment until the end of the legal process. Nor does Congress, which should feel free to impeach even before any criminal charges are filed in the courts.
I don't need more evidence to know that Trump is corrupt. He has been convicted of fraud, he is a confessed serial sexual predator, he has been exposed as a serial adulterer who has unprotected sex with porn stars while his wife is at home attending to their newborn son, he is surrounded like a mafia don by confessed and convicted criminals, he has no relationship with the truth, and he admires dictators. What more do you need to make a judgment here about the man's character?
So yeah, we reserve judgment until we have enough evidence to "convict," but I have that now.