See my comment above. Basically, this would be challenging to do even at Google depending on the level you get promoted to and requires total dedication to the above, i.e., saving aggressively.

I think the advantage of getting into Google right out of school is that you can start on that path right away.

I didn't get to Google until working for over 10 years at other companies and as such and I wasn't really planning for such a goal so, for me personally, I will be lucky if I can retire when I am 60.

Most people are looking at never retiring at this stage. Retiring in your 40s puts you in a very exclusive bracket.

See my comment above. I think this might be rare even for most Googlers, but it is possibly doable depending on on the person.