Google was one of the first tech companies to pay so well that people switched industries to get into tech both to work alongside brilliant people from various backgrounds and to make a lot of money.
Before Google, it was very rare for an independent contributor/software engineer in tech to retire early if you didn't hit the startup lottery. Sure, people who joined Microsoft pre-IPO did well, but it's not the same as now where a good 10-15 year run at a FAANG allows many to retire early (if they choose).