What you do is not terribly important, but your contacts are.
I had a really neat setup for developing API and apps really quickly 8 years ago and it didn't go anywhere. All my clients were getting that and I was able to get fixed contracts done very quickly (increasing my rate) but I never managed to build an audience and find a way to productivize it and sell it. Eventually I went out of sync with some clients who needed something else and I didn't want to pay the effort to maintain it, so I just use other off-the-shelf solutions.
The primarily driver in that change was that I got new contacts and working experience together with people earning more and I was able to charge a higher daily rate doing whatever needed to be done.
Most of the jobs don't find their way to recruiters, they're just word of mouth and they can be quite lucrative.
At the same time, even if I was making 500£ per day, I knew people making 900£-1000£ per day. Some of them were just incredibly specialised on something domain specific (there was a bit of a stereotype, the Java guy with finance experience contracting for a bank with water to their neck and charging 1000£ per day), but some of them were just your average frontend engineer who contributed to some cool sounding famous framework.
I managed to charge high amounts in some specific circumstances where my knowledge was needed, but I never managed to network with the people routinely making 1000£ per day doing your average job.
Recently I got to those numbers, but I think that happened mainly because my circle "upgraded" (aka people who trust me got into position of power with high spending power) and because of covid inflation. Money is just not worth much when there is so much of it around and assets keep growing.
Hope you find that helpful in your contractor career.
The second part of your post is about preferences. Preferences changes.
I used to enjoy city center life as well, partying in the cool places, going at tech events with famous people.
After a while going out started feeling tired, so I settled down and started a family. With a family a big city is not very attractive. I moved to a smaller city, so I don't have to drive and I pay significantly less for the same property. The events are much worse compared to city life, but all the amenities are there, walkable distance.
I'm in the process of moving to an even cheaper location, so I can buy an even bigger property and have a nice garden. There are also some tax, weather and societal considerations into that - but I'll have to start driving again. This may have felt like a big pain in the past but it's manageable right now.
If you read between the lines of the original posts, he's basically recommending to work smart so that a little of your work goes a long way economically and to live somewhere relatively cheap, so that it's easier to retain more money. It doesn't necessarily prescribe your life.