It's not (mostly) to salve their consciences; it's fundamental to their avoidance of the Resource Curse/"Dutch Disease". Norway, unlike just about everywhere else "blessed" (and I use those scare-quotes intentionally) with oil and gas, anticipated the value of not getting high on one's own supply: they have some of the most heavily taxed vehicle fuel in Europe, as well as strict limits on how much oil/gas tax revenue can be spent each year with the rest going into an enormous investment fund.