What I'd argue is that your observation is a form of survivorship bias. Of the very small people who manage to succeed without a degree, those people will likely have a great deal of drive, self-motivation, and other traits to compensate for that lack of degree. I'd then argue that in the long term, those traits end up having a much greater impact on your ability to succeed than an education.
But that doesn't mean not having an education is overall a good thing. The majority of people without a degree will be absolutely incompetent software developers compared to those with a degree... you would just have never met them because they don't last long enough to work with you.
If a degree or formal education has been used as a barrier to restrict access for any time only the strongest and most driven of the degree-less are going to persevere and make it.