Same way Hitler did, by appealing to victims of power, and anti-Western sentiment (though I think bin Laden is a student of Hitler, I don't think he's an equal).
Saudi Arabia is having real problems with their fundamentalists and youth. There's a lot of poverty, plus the real view that the current King is there only because the US put him there. If the King gets overthrown, the youth and fundamentalists will look for someone who is anti-US, and bin Laden has a fairly good name with the youth, plus a proven track record for getting things done. Like the Nazis, bin Laden is good at telling the poor just what they'd like to hear -- that they're chosen and their problems are not their fault.
Overall, I think it's a long shot. But, I don't think bin Laden thinks it's a long shot.
Re:
Saudi Arabia is having real problems with their fundamentalists and youth. There's a lot of poverty, plus the real view that the current King is there only because the US put him there. If the King gets overthrown, the youth and fundamentalists will look for someone who is anti-US, and bin Laden has a fairly good name with the youth, plus a proven track record for getting things done. Like the Nazis, bin Laden is good at telling the poor just what they'd like to hear -- that they're chosen and their problems are not their fault.
Overall, I think it's a long shot. But, I don't think bin Laden thinks it's a long shot.