I took a major pay cut so I wouldn't have to work with certain popular commercial languages ever again, and now enjoy working in a small studio where we create DSLs in Scheme. Every week I discover something new about Lisp and then use it on independent hobby projects, whereas before I didn't even want to look at a computer after work.
Small stealth mode startup in Vancouver, Canada that does custom DSLs for the oil & gas industry. I found the job on my local CL, they were advertising looking for anybody who had read SICP, or had experience doing functional programming. It doesn't pay a lot but enough to live comfortably while single plus I get to hack around in Scheme all day, though now they want me to learn Haskell too.
I work 6hrs a day usually and spend the rest of time experimenting with my own DSLs for future side projects or enjoying life whereas before I'd go to work before the sun came up, work in a windowless office under constant unachievable deadlines then leave at night. I had money but no life.
A job for the oil & gas industry which requires SICP level coders which doesn't pay well? I'm not sure what to think - that that industry really doesn't pay well, or that you need to read patio11's guide to salary negotiations.
Because if he's making a below-market salary as it sounds like, he could be doing better. With a higher salary, he could have more savings, more security, more easily afford a family or the things he wants, donate more to charity, spend more on personal hobbies, etc. Money has many uses.
And I could ask you the same question: the startup founders and oil industry would live comfortably enough if they made a little less and paid him better; why is that not enough? Why should they be making more?