You need to remember that a lot of people drive drunk because of peer pressure, and they don't really have much of a choice unless they want to destroy their entire social lives.(though personally, I wouldn't mind losing a bunch of douches that make me drive drunk, but I'm more apathetic to friendships than most people)
They could be good people at heart, but they make one mistake that puts other peoples' lives at risk. While they need to be discouraged from ever making that mistake again, so they should be at least jailed for a few months; I think a lifetime jail sentence is a bit excessive if they haven't actually done much damage, or killed anyone. We should reserve lifetime sentences for people with actual motives, or psychopaths who murder for fun; not for mostly innocent people who make one terrible mistake.
However, I do think people who have been caught drunk driving repeatedly should bear a very long jail sentence, and a lifetime ban from driving, because at that point; they're clearly just douches with no care in the world.
I do think that the limit of imprisonment for killing someone while drunk driving should be removed though.(so that courts can give people life sentences) It's kinda stupid that it's limited to 14 years /: