Lots and lots and lots of people make no. 1 work. The issue isn't whether it is a monolith or not. The issue is whether it has good or poor internal architecture.

No 1 can scale to 1000 requests per second. One machine, one db, one application. It is totally doable because so many people do it.

It's just not sexy and doesn't pad you resume. It's boring stuff that just works.