Those that are running full nodes are likely spending ~1k/month in hardware, and putting some time into running that node.
There are VERY FEW that are running full nodes. Running a witness node does not require ANY support/time and very little $ (less than $100/month).
1 node baremetal in general costs exactly $100.
If you run 10 it costs... right...
But yeah there is only 1 signing yeah.