Absolutely nothing he has said in this post has contradicted anything said about this position. He flat out states he is underpaid and has no work/life balance.
It sounds like you are surprised that there are people who are not like you. There are lots of people in lots of companies that prefer working longer hours and maintaining their social circles at work. The author of the post says he's one of those guys, and he took a pay cut to work there. He worked at Amazon, he's not dumb and he's not being willfully exploited. So one must assume that he did it because he wanted to. He could have left long before now.
Saying that he somehow has a problem because that's what he wants in life is pretty judgmental. Do I want to work that way? No. Do you? No. Does it mean he has a "problem" because that's what he wants? No.
If you work long hours, you should be paid accordingly. If you want to volunteer your time to make a company profitable that's your choice but I reserve the right to believe that's dumb/wrong. It also devalues the work of every other developer.
The fact that he's ok with that is the problem!