I think one could argue that Walt is quite the altruist. He just has a skill set that he knew how to exploit, and he actions while illegal would have helped his family prosper after his inevitable death.
If you're an ends justify the means kinda guy, then yeah. But think about it, for Walt to help his family, 15 people had to die before he could achieve his goal. You can add 150 more to that number if you're talking about the indirect consequences of his actions. Add on top of that, all the countless lives that have problem been ruined by his product.
Then you have to question why he had to do it in the first place. If it weren't for his overbearing sense of pride, he would've made millions alongside Elliot at Grey Matters.
What it all comes down to is that Walt put himself into the position he found himself in at the beginning of the show, and he put himself into the situation he's finding himself in now. All the justifications he came up with were nothing more than excuses to fix his previous mistakes.
As for altruism. He says he's doing it all for his family, but from season 3 on, I've always figured Walt never did anything that didn't somehow stoke his own ego. I mean he could've worked for Gus for 3 months, made 1.5 million dollars, and set his family up for life. But he didn't like being under someone elses thumb, them getting all the credit for his hard work. He wanted more. So he went farther than he ever should have, and ended up being ruined, once again, by his own overbearing sense of pride.
Dude's a bastard, man.
...and yet despite all that...
Heisenberg mode: Activated.
...you just can't help but go "**** yeah" whenever you see him get ready to do something drastic and awesome. The closing shot of tonights episode probably made all of us tingly in our nethers.