I'd say thats how they see society and their role in it more generally. Doing God's work is a surprisingly directed graph. It applies also to the broader banking world, but investment banks being the most lucrative (when not bailed out) attract talented people that in principle can close the loop and return something important back (much more so than the "sleepy" commercial bank or credit union).
It would interesting if the above (potentially biased) view could be backed up by computing an open source leech ratio per industry sector. The amount of open source code used versus the amount contributed.
NB: a high leech ratio does not necessarily make you the worst offender. If your business model is evil no amount of open source contribution will wash it out