IME, self-taught people tend to have solid business acumen too. The getting that first job with no credentials forces you to 1) figure out a good idea for a product, 2) build it, 3) sell it. Even if it's a small/toy example, like a website or app, and "selling it" amounts to showing it off in interviews.

In contrast, most CS grads can get a good job after a whiteboard session and a quiz.

I'm not saying that one is better than the other, but there's absolutely some self-selection going on among self-taught engineers.