- used nuclear weapons against noncombatants not once, but twice, in spite of the fact that it was clear the Japanese were ready to surrender
- purged civil society and the trade unions of the left, getting the ball rolling for McCarthyism
- plunged the U.S. into an utterly pointless global conflict with the USSR, PRC, and the rest of the Eastern bloc in spite of the fact that the latter group was not ever interested in 'world domination' by the time that the Stalinist counterrevolution had taken root
- fought a pointless war in Korea that killed hundreds of thousands of people
- pretended to oppose the Taft-Hartley Act (in reality, he'd have signed it if it had given him more discretion in terms of settling strikes by force) then used it repeatedly to force workers back to work, including drafting steelworkers into the army, etc
- incredibly corrupt
- allowed Israel to be a thing
Striking the unsupported, vague assertion of being "incredibly corrupt", every other thing on this list is why Truman was a massive FF and one of the best Presidents America's ever had.