"President Gerald Ford pardoned President Richard Nixon, who had not yet been charged with anything."

Trump knows he will go to prison as a civilian.  His only out is to have President Pence pardon him before the fact, after he resigns. As his chances for reelection wane, he will be more likely to do that. Especially when coerced by members of his own party, as Nixon was.

His need for survival will override his usual stupidity