It's not that college is always bad, it just comes with negatives that have to be weighed against the positives. The standard approach is to assume that instead of going to college (whether at 18 or mid-career) is to assume that the person will do absolutely nothing productive with their free time, accept the same stagnation and all other negatives that come with the educational process, and that they will then compete toe to toe after the one has completed college and the other has just waited for them to finish.
But in the real world, someone ambitious enough to have gone to college for career reasons is also ambitious enough to work harder at their jobs, done a side job, gotten certs, learned on their own, moved on to another job, or so forth. Those are the more realistic actions of the other person that had the option of college. So when making the comparison, you have to look at those opportunities and look at the opportunities from the degree process and weight them in that fashion.