> Google employs ~30k software engineers, each making a ridiculously high salary
I think current google salary can even be below market average.
> yet 80% of their revenue comes from ads (a field which they have a monopoly over).
ads is just way of monetization, actual product portfolio is very diverse.
> The products people use every day (Gmail, maps, search, chrome) are nearly 15-20 years old at this point.
My understanding is that they switched from idea of building tons of lower quality products some of which survived to full focus on fewer areas. Current focus is AI and cloud, where there is enough space for innovation.