Those companies have one heck of a combined market position and it is all built with software. I would say their software engineers are paid more but I doubt that "overpaid" applies.
Think about what your CTO could do in that setting and realize that he's probably worth more to FAANG shareholders than to you hence the salary differential.
For the record, I do not work at a FAANG.
When people on HN discuses salaries, or I see a job posting from a Silicon Valley company I can't help think that we don't even pay our CTO that much. Frequently you could get two developers for the same price here in Denmark.