There is some middle ground of corporate lawyers and partners at smaller but relatively prosperous practices. But, yes, for the many it's making partner at a white shoe firm which tends to require attending one of a fairly small number of law schools and getting a prestigious clerkship--or you're running ads in the subway.

You do get supply demand corrections over time though. If you know you'll be making minimum wage if you didn't go to a top law school a lot of people would stop doing so.