It looks like madness because it's something that's almost completely absent from politics around the world: thinking past the next election!
Ok, the government has this oil money what should we do with it? Give everyone tax cuts? Build giant vanity projects? Throw a year-long nation-wide party with a kilo of cocaine for every household?
Nope, let's invest it into a government owned diverse market fund so the social security of our citizens is sound for generations to come.