As a college dropout who dropped out 20+ years ago due to simply being on the wrong course (I spent all my time in the computer centre learning about UNIX instead), I’d like to take issue with your assertion that simply having not completed a university degree is a red flag. As with all things, it might be or it might not be.
Someone who dropped out of college in order to take a highly-paid job at a startup because they felt they didn’t need to study any more may fit this model, and I can see how that is likely to lead to the kind of “me supremacy” that infests the mind of so many men in tech. It’s certainly a danger signal if they tell you at interview that they left because they felt that university was a waste of time. That’s a sign of someone who simply doesn’t understand what university is for.
On the other hand, a lot of people who drop out of university do so for other reasons. They don’t have a highly-paid job to go to and instead have to come to terms with their own intellectual mortality. They’ll have to look for more junior, less well-paid jobs and prove their ability by doing well there before they can do anything else.
At least in my own case, although it still causes me hassle decades later I can’t help but think that dropping out was the best thing that ever happened to me. It didn’t feel like that at the time, but the resulting career has been a lot more interesting and fulfilling than it might have been had I scraped through my course, landed an engineering degree and gone straight into graduate training in the corporate world. More importantly than anything else, it also taught humility. Nothing does that more than learning that it’s possible for you to fail – a particularly important thing for a comfortably middle-class white kid to learn.
College dropouts invariably face discrimination at hiring time simply because they don’t check the all-important “graduate” box recruiters love to see. They’re more likely to have to be self-taught and persistent as people won’t hire them for roles that are specifically designed for training people who have recently graduated – they may have to jump straight in and start performing to prove to their colleagues that they are “worthy” of being there. They know how hard it can be to succeed in the world of tech if you don’t fit “the template”. Dismissing them simply based on the lack of a piece of paper seems… unimaginative.