That's just for insurance. You still going to be paying 20% of the actual medical bill. You can easily run up a $100k bill in a week.
That leaves care that doesn't get covered by insurance of course, but people aren't on the hook for 20% of the bill that insurance covers.
I think you're still on the hook for the full coinsurance amount if you're at a hospital and a doctor from out of your network happens to step in the room without telling you they're out of network.
Totally fair to always discuss the huge caveat of out of network providers getting involved without any opportunity to refuse their care alongside the out of pocket maximums for in-network services.