Your friends probably aren't engaging in "greed is good" themselves, just responding to the economic conditions created by people who are engaging in it.
In the American cultural headspace, "greed is good" refers to a very specific brand of robber-baron capitalism. It's a doctrine that was first given academic legitimacy by the University of Chicago's school of economics, then put into practice in the 1980s under the Reagan administration, and nowadays its loudest proponents are Musk and Thiel. It's an economic theory that lionizes extractive behavior by the economic elite, with some bullshit trickle-down argument that's too convoluted to be worth explaining here.
It creates an environment where everyone had to do evil shit just to put a roof over their heads, a self-regulating race to the bottom. Your friends are likely just unwilling participants, a side effect of "greed is good" rather than doers of it.