Ah, my friend. "Ah".
One could argue that Axl's self-destructive nature really fleshed itself out as he realized that Guns N' Roses' popularity was slipping due to the onslaught of grunge. The riot was definitely a big thing. I was only 10 or 11 at the time, so I remember very little of the specifics (and will go read up on them now), but they definitely could have weathered that had they continued to produce quality music.
I think the biggest problem was the departure of Izzy Stradlin. Besides writing &singing the best Guns N' Roses song ever (14 Years, if you're curious
), he was, simply, a staple of the band. He might not have been as visible as Slash or Axl, but he was equally important. The best songwriter for the band, a good singer anyway, good rhythm guitars... losing him was a tremendous blow.
I really think this all started though with Nirvana and grunge music in general. GN'R was at the top of the world and saw it being taken from them. Shit, Metallica wasn't even as big as GN'R in '91. Axl realized they were in for a big fall and hit the bottom.
That's my opinion, anyway.
P.S. - Tony and I owning the boards today. What's up with that?