Raising rates is a poor idea when so many people are suffering economically. Trump is just mad at Jeff Bezos, the head of Amazon.com who also owns the Washington Post. In the past, presidents haven’t meddled in post office rates but everything is political to Trump.
Killing USPS would also eliminate mail-in voting which Trump opposes. Republicans want to make it harder to vote to preserve their power. They also want to privatize it but don’t understand or care that businesses would not want to take on money-losing routes.