The Wizard, like most of the main characters first appeared (black&white) as Professor Marvel, a conman fortune teller / mind reader.
Once discovered as a charlatan as the Wizard, he admits to being a fraud, imposter and a humbug. What he gives the Lion, Scarecrow, and Tin Man are worthless items. You could say he helped them to see they had the traits they desired already in them but he didn’t actually do anything. He was impotent to actually help. Even taking Dorothy & Toto in his balloon back to Kansas fails miserably.
He also claimed he wasn’t evil but he wasn’t any good to anyone but himself. He was incompetent and he tried to hide it. So, I wouldn’t call him evil per se (other than lying) but he wasn’t a ‘good guy’ either.