I'd be very surprised if most FAANG engineers aren't millionaires after 5-10 years. The caveat being that houses in the Bay Area cost a lot more than a million...
One of my buddies who works at Google basically lives in a hacker commune so he can pocket most of his earnings post tax. Not sure quite what he does with it.
Sits in an account until the day that he gets suckered into marriage and home ownership
After that a messy divorce and funds are in lawyer and exwifey account and back to the commune
Commune will be 2beaucoup after a tech-salary divorce, only solution is evading the lifetime alimony police by sleeping in the desert, where your only friends are scorpions and your only food is the same ;)
MGTOW for life!
Microsoft, Amazon, Google, and Facebook all have significant Seattle-area presence; it's still expensive, but noticeably less so than Silly Valley, and you can live close to work yet have a Walk Score in the double digits. (And in fact a good score.) MS has a non-negligible number of jobs in lower-cost areas of the US (e.g. Fargo, Las Colinas, Atlanta); Apple is expanding in Austin; both Apple and Google have an increasing number of offices in lower-cost cities.
FAANG pays well, but not necessarily more challenging