On a 64-bit system, 10 GB of address space is nothing.
10 GB of RAM is certainly something though. Especially in current times.
Except if those threads are actually faulting in all of that memory and making it resident, they'd be doing the same thing, just on the heap, for a classic async coroutine style application.
If you have hugepages enabled, all of those threads are probably faulting in a fair amount of memory.