This is an interesting point. Can anyone from the inside estimate the annual budget for Chrome? A billion sounds like a lot. That implies: 1b / 250k = 4,000 (expensive) developers. I guess at least 1,000 well-paid people are involved, so hundreds of millions sounds more likely.
250k is conservative for employee cost. A staff engineer at Google can reach 1 MM total comp. And add in all the overhead a company has (real estate, free food, perks, taxes, etc)
500k-700k is a little more realistic. 1500 employees across all domains (engineering, marketing, product management, customer service, etc) isn’t a huge number
Mozilla at least at one point had 1,000 and is and always was chronically underfunded. 4,000 seems about reasonable. Keep in mind it's not 4,000 engineers, it's PMs, managers, UX, Infra, there's a lot more to software development that just line engineers.
