Ask HN: What is the difference between managing 10 and 1000 containers?

I am trying to wrap my head around scalability.

From a dumb perspective, managing 1 container is different from managing 'n' (where n>1). I can understand that part. I guess I can even extend it to where 'n' is greater than 2, and certain decisions have to be made.

But what is the difference between 5 containers and 50 or a thousands? I'd think at 5 containers you have already dealt with all issues around multi-tenancy. What changes from there to 1000 containers?