Man, if you think that was excessive, you don't even want to how many federal agents investigated John Gotti, and he was just one guy.
Gotti was a whole different ball game, and he was not just one guy.
He made the feds look real bad, avoiding their numerous attempts to end his career. He beat three of their prosecution attempts, and basically laughed in their faces. He was high profile target, and there was big money and several homicides involved here. Not only that, he had dozens of high level criminal types assisting him. Without his boys, he was basically nothing.
He was a hard nut to crack, and if it wasn't for planted electronic bugs, he would have dodged a 4th prosecution attempt.