Because he’s got the US Attorney General, the DoG, the FBI, the CIA, the NY State AG, the Fulton County, Georgia DA, and the NY County DA pressing their frivolous charges and, as you say, he’s got the Presidential Pardon power. As a sitting president he can’t be indicted and probably will never be indicted. He may be impeached but it is doubtful enough democrats in the Senate will vote to convict. Even when they know he’s guilty as sin.