Ask HN: What could a single company do with 1000 developers hired in a year?

In a recent StackOverflow podcast[1] a guest mentions a conversation with a recruiter who is trying to find 1000 Ruby developers in 2021 for a single client. It was not really discussed, but if anyone has any insight I am very curious:

1. What kind of company/project can benefit from 1000 developers being added to it?

2. What kind of onboarding process could handle 1000 new developers in a year?

3. Are there really a thousand Ruby developers in the world who are likely to change jobs in 2021?

[1]: http://stackoverflow.blog/2021/05/14/podcast-338-why-is-it-so-hard-to-find-ruby-developers/