I am a researcher and I try my best to be neutral about politicians by looking at the big picture and long term effects. Hand on heart, I cannot tell why people think Trump was a bad president. He found his way around the absolutely tricky, delicate balance of Middle East peace. The issues we see now with Israel, Afghanistan etc are not a coincidence - the entire region has been destabilised quite significantly in the last eight months.
The refugee crisis will now get worse (and we have more to come if my assessment of the situation in Iran and Syria is accurate). Trump destroyed a lot of the ISIS stronghold in Syria and there is now a high chance they are coming back.
The Mexico border issue has been going on since Obama's first presidency - it didn't get better or worse in Trump's time; it got worse in Biden's time.
Financial institutions benefited greatly from deregulation during Trump's presidency - innovation and better consumer products as a result.
Reforming US immigration in a way never seen before, for the benefit of Americans (I am sure people outside the US will disagree with this, but the H1B visa process makes a lot more sense now, with more Americans being hired for the same job instead of foreigners, for example)
Criminal justice reform.
Honestly, keeping the 'man' aside, why don't we recognise that good things happened during his presidency?