He most definitely has. Heck, spent some of that on founding a rocket company.
"The rocketry has always been a negotiation with my wife, understandably so, where. She has always insisted I not be one of those celebrities that squanders all of their fortune being high on the hill and then being penniless some day, so, rocketry has always had this carved out area, where, "this is John's crazy money" while "All of this is to make sure the family is well taken care of and John's not going to be begging for work some time." But I basically expended my crazy money on Armadillo. So I don't expect to see any rockets in the real near future."
Armadillo Aerospace went into "hibernation" in 2013 and sold off its assets.
1) id Software sold to Zenimax for $150 million. [1] John Carmack was a large shareholder at the time and claimed a year ago that Zenimax still owes him another $22.5 million. Adrian Carmack owned 41% of id when he was fired & bought out of the company in 2005. From that ownership consolidation, it's very likely John had 1/3 or more of the company when it was sold to Zenimax.
2) Oculus was purchased for $2 billion. $400m in cash and 23 million shares of Facebook. Those shares would now be worth $4.2 billion. Carmack owned a position in Oculus pre the Andreessen Horowitz investment. A 1% stake would have been a substantial windfall.
3) He earned a large amount of money from being an owner of id Software from the Wolfenstein days forward.
According to Wired, he put $8m into Armadillo before closing it down. The id sale alone covers that cost at least twice over after taxes.
[1] https://arstechnica.com/tech-policy/2017/03/john-carmack-zen...
1: Biography of id software, obviously heavily featuring Carmack. Highly recommended.
This is not me inferring Carmack's wish to work there are much as it is just assembling things he has tweeted in the past.
He famously bought a Ferrari and turbocharged it[1]. He doesn't _need_ to work for a living, he's doing what he wants to do.
[1]: https://spectrum.ieee.org/tech-talk/transportation/advanced-...
The only plausible explanation is that Carmack writes on Facebook out of his own free will.