As N of people → ∞, chances for software to break → finite maximum. And for good enough software you should consider that maximum already regardless of the number of users.
I don't believe such software exists. (And, to be clear, I'm writing from direct, day-job experience.)
EDIT: I take it back. SQLite, cURL. Maybe.
EDIT2: I can't reply to the SEL4 response, so here goes. I'm a huge fan of verification tools, but consider the Spectre class of bugs. Verification is always done wrt a mathematical model that you've defined after inspecting the world and writing down the properties you want to track. But the world changes, and the chance that the world changes increases with the number of users of your software. That's the nature of the beast.
When I had a reply I couldn't reply to, I opened the reply separately in a new tab, and there I could reply to it, try this.
It's a bug in the processor that causes a bug in the software. It's not a bug in your idealized mathematical model, but try telling that to the people who paid you not to leak private keys.
I see my job as an engineer to be to create a product that satisfies the user's expectations (which in this case are eminently reasonable). It matters not one bit that I can point the finger to the chipmakers. I'm still selling something that I now learned doesn't do what I said it would. It's still on me to fix it the best I can. If I care about the product quality, that is.
Not my business to decide what you think is reasonable. That's just what happens in the world, and what (in my view) good engineers sign up for.
Why do you think so?
What choice? I have to fix bugs today as they come.
I think that this is a bad analogy to hardware, though. Polished steel roads are unreasonable to ask for, but bugless processors are reasonable to ask for.
I’m software we deal more with curses than miracles. Those happen every day too.