I am skeptical of claims like, "you will never need to handle 100k requests per second."
Never is a long time.
Don't get me wrong. If I got that as a requirement, I'd question it. It's about the same number of requests per second that Google Search handles. So it's VERY up there in term of load.
There are a lot of software engineers at these large companies, and they so they do need to handle it.
So I wouldn't say "never", but I'd be skeptical of the request if it came in.