What if he doesn't pay back because ₿TC went down instead of up and he doesn't have it anymore? Ofc he needs the next $10 because now it will go up for sure and he'll make the other $10 back as well... :)
https://apps.newyorkfed.org/markets/autorates/tomo-results-d...
I'm trying to avoid pedantic arguments and focus our discussion on the safeties and how effective they can be when the unthinkable happens.