These guys sucked so bad that Magneto left them, or maybe Magneto was just tired of losing? Either way Magneto gather
a completely new Brotherhood to fight Captain America while he went off to do something evil but when his new Brotherhood
couldn't beat Captain America despite a 5 on 1 advantage, he left them and the Brotherhood of Evil Mutants II siezed to exist.
Sadly it would be 30 years before Magneto would take his place as leader of the Brotherhood of Evil Mutants again.