Just curious, but what makes it not a legitimate job?
Simple:
You have no contract, you have no set amount of hours, no hourly wages, no 401k, no health/dental plans, no travel expenses, no insurances, absolutely nothing.
You also have no certainty, you can never get tenure, your income soley relies on the generosity and views of others. If you ever have to start soliciting for an actual job again, you also will have to explain a hole of several years in your resume, good luck explaining that your only marketable skills are "good at gaming" for example. You do not develop as a marketable person for a company, no new skills, nor do you get a payment increase over the years, or get extra perks.
Depending on your level of success, I'd say the entrepreneurial skills of running a profitable channel is a pretty good selling point. Most streamers have backup plans or side gigs also so they aren't confined to streaming as main income.
But yeah I'd still say it's less than a job and more of just a smart financial move to capitalize on the modern craze of just watching other people play games and make money off the ad revenue.
Gaming isn't the only field youtubers can take part in.