Nader was an egomaniac; some of his most ardent followers begged him to get out of that 2000 race when it was apparent how close it would be, but he was too high from the crowds to care.
Nader didn't strike a blow for anything in 2000, and neither did his voters. There were 2 viable choices in that race: Bush and Gore. By about a million miles, one represented values that were much more aligned with what Nader values than the other. The fact is that it was a race decided by about 500 votes, and, as a result of Gore losing, we went to Iraq & are still there. You do the math.
Don't even get me started on everything else. Nader also had very strong environmental convictions. I wonder if the past few weeks worth of midnight rule changes by the Bush admin, that far exceed the worst corporate polluter's fantasies, still have him saying "Bush & Gore are the same."