Plus, working part time in software still means that I make good money.
If I could work for a "regular" software company but only work 20 hours a week (and be paid 50%), I would definitely do it.
For what it's worth, I also know someone who for a while worked 6 weeks on 6 weeks off - he was kind of one of those fabled 10x developers and so had negotiated something special with his employer. Another commenter mentioned something similar; working 40 hours a week but for only a few months a year.