Numerous folks have made versions of this point recently, but it bears repeating:
It's ironic that so many folks on the left who are (rightly) insistent that humans are motivated by many more things than narrow financial self-interest then end up being unable to believe that libertarians or conservatives who disagree with them about public policy are motivated by anything but their own financial self-interest.
The Kochs are the obvious example of this, but I'm pretty sure almost every libertarian or conservative public intellectual has experienced this form of argument at one time or another. I know I have.
Yes, you're right, my progressive friends. Humans are motivated by a whole variety of things other than money, including the desire to make the world a better place. Please consider that this correct claim might apply to people who disagree with you absent clear evidence to the contrary.