OK, sure. Charging more gives you access to the better class of clients. At age 23 I started out doing shitty freelance PHP work, included a bunch of fixed-price projects. Later on, at age 26/27, (I worked full-time in-between), I spent a year contracting for digital agencies at twice my 23-year-old rate, and had a much smoother time.

So I know first-hand the benefits of "going up in the world" and getting into a higher-quality network of clients. I now look at websites like ClientsFromHell.com and see freelancers managing their careers really badly, not knowing they could be doing much better.

All that is true but it's not what came through in your original comment. You could have said "Ouch, poor guy, he got shafted, but all of this was avoidable. He should start acting like a business rather than a temp worker, and aim to build up his skills, learn to market himself, and find a better class of clients". Instead, you victim-blamed him, and poured scorn on him for speaking out.