Poor bastard. By all accounts, an exceedingly capable engineer - the guy just didn’t know what we know now. Hell, the invention of CFCs was motivated by a genuinely praiseworthy impulse - earlier refrigerants used to kill people when they leaked. Midgley helped to stop that, and he had no way of knowing he’d be damaging the ozone layer.
Actually, the guy was genuinely evil. He knew about the dangers of lead poisoning, he suffered from it himself, but lied about it to the press. He may not have known about the danger to the general public, but there were cases of hallucinations, insanity and several deaths at the plant he worked at.
He was unlucky on CFCs, their effect on the ozone layers wasn’t known until much later.
According to Bill Bryson’s Made in America, the guy who invented the shopping mall originally intended it as a place to foster a sense of community and bring people together. He died horrified at what his invention wrought.