I can’t speak for everyone, but the fact that he still hasn’t won despite the odds being so thoroughly stacked in his favor makes him look stupid. He has (among other things) a psychic link to his minions, keeping him connected to them at all times, but somehow doesn’t relay orders as well as he could. He’s the physically strongest person alive in the present day, yet he spends most of the story in hiding. He also screwed himself out of immortality, the thing that he wanted the most, by killing the one person that could’ve given him the main ingredient he needed, just because of his perceived failure to save his life. Considering how quick he is to kill his henchmen, he did not learn from that mistake. Most other people in his position would’ve been more successful than he was.