It's hardly justifiable to imply that the entire military defense of the United States is simply to protect "$70 billion in assets."
If the entire monetary system of the US were replaced by BitCoin, do you think there would be no need for an army? Would the block ledger be "protecting" all the actual physical assets, land, and people?
You can argue over whether the US should have a military, or its size, but to imply that it's just to protect the dollars isn't going to sway anyone in an argument.
The protection to value ratio is drastically beyond 1:30. Your value calculation is worthless if it only takes into account annual GDP.
The total value of the United States, all assets, private and public, is closer to $250+ trillion [1]. That's a 1:400+ ratio.
US household assets alone are near $95 - $100 trillion at this point [2]. That's a ~1:160 ratio just for household wealth.
You missed by an extreme amount in your speculation and that's just based on present value. If we were going to be rational about it, we'd want to consider that present military expenditures help to keep safe future value creation (I'll note that I'm not arguing whether those expenditures are $n too high or too low).
The military is also not the only protection system in place. You are right, just considering the GDP is too limited, but considering just the military is also too limited. Police, fireman, courts, security systems, the SEC, locks, alarms, etc all contribute to protecting assets in the US.
It's a hard number to measure. Bitcoin inflation has a fixed measurable cost though (12.5 coins per 10 minutes), if that's acceptable to you for the benefits you get, then it's money well spent burning electricity.
If the entire monetary system of the US were replaced by BitCoin, do you think there would be no need for an army? Would the block ledger be "protecting" all the actual physical assets, land, and people?
You can argue over whether the US should have a military, or its size, but to imply that it's just to protect the dollars isn't going to sway anyone in an argument.