Eh, this isn't a great theory especially for the poor.

As a higher income individual I conversely seem to have a lot of time to study and am not given a constant stream of work I must complete every moment. I also have the benefit of working from home and being able to spend a lot on training and upskilling.

When you are poorer you typically don't get this. The vast majority of your income is spent at the end of the week. Your job gives you zero time to explore and learn more. You likely commute and and may have a second job to make ends meet.

Just saying 'learn to code' here doesn't address the systematic issues.