I used to work at a Fintech company where we had around 1-20k concurrent active users, monthly around 2 million active users. I forget the RPS, but it was maybe

I used to work at a Fintech company where we had around 1-20k concurrent active users, monthly around 2 million active users. I forget the RPS, but it was maybe around 200-1000 normally? We ran on bare metal, bash scripts, not a container in sight. It was spaghetti, granted, but it worked surprisingly well.