Why did Dave Mustaine leave Metallica?

Answer 1

Dave Mustaine did not leave Metallica, he was kicked out because of his drinking and substance abuse. He was known to have an aggressive behaviour and frequently showed up to practice drunk and incoherent. Mustaine also had anger management issues that led him to assaulting James Hetfield. Also he drove the original bass player Roy McGovney who was a high school friend of James out of the band after a fight they had.

Mr. Mustaine was shooting heroine, cocaine, and using any chemical available. He did not like himself at all. The boys fired him but I still love Megedeth.

he did like himself, but he took drugs to ease pain probably

wrong: Hetfield and Mustaine both wanted McGovney out of the band because they believed he wasn't contributing enough he was just following. Also because they seen Burton play at a show called whiskey a go go in a band called Trauma, and were blown away by the way he used a wah wah pedal.

He did NOT "frequently" show up to rehearsals drunk and/or incoherant as stated above. This was not the cause for his untimely exit from Metallica.

The actual incident that sealed his fate was sparked when McGovney and Hetfield unleashed their "aggressive behavior" on Mustaines dog for jumping on hood of McGovneys car, by kicking him repeatedly. I would not consider defending an innocent animal from two idiots "aggressive", in fact any other reaction would be cowardly. So this whole rumor of Dave having an"aggression problem", is also inaccurate. Even at his worst, Dave is an intelligent, rational human being, many try and make him out to be otherwise becasue they are

jealous, or threatened by him because of his level of musical ability.

Answer 2

Because Dave poured beer on the pick up of his bass. When Ron plugged in the cable, the Bass Guitar blew up. After that, he asked James, Lars and Dave to leave his house. He said he couldn't take it anymore.

So yeah. The answer is because of the young Dave Mustaine, who was out of his mind back then.