This is one important concept I've learned from Sebastian. It used to be a central message on his "About" page.
I would like to unpack it a bit, though. I hope SM himself will chime in here.
What does it mean to demand to be treated well? What are the ramifications? What does it mandate that YOU do in return?
One obvious example would be Sebastian's going mano-a-mano with Cathay Pacific and coming out at least somewhat victorious.
One example from my own life: there is a chain of grocery stores in Sweden called ICA. I had been going to my local ICA regularly for, oh, 20 years or so. During the last few years or so I started noticing that the staff were being consistently rude/hostile to me. They would be gruff at the check-out and they would do little passive-aggressive things like just plonking the change down instead of handing it to me. They would treat the next customer in line differently: smile and hand the change in hand. Maybe I did something to deserve this. Beats me what it could be, though. I didn't really consider this of great import - after all, I try to be above petty shit like that - until I realized that I could leverage this for personal growth. So I made a decision that I will not shop there anymore. I rather spend an extra hour to go the supermarket, or I pay ridiculous prices at the gas station. Doesn't matter, it's the principle that counts. By so doing I am (hopefully) starting a pattern of ruthlessly culling things from my life that don't serve me, even if it's uncomfortable for me to do so. And I think THAT is a useful habit to develop.
Here is a related concept: speaking your truth, always, is functional self-esteem. You may not FEEL it at the time, but you are DOING it.