I didn't ask it was fair to compare the two. Obviously the strength of the US economy is the main driver for the value of the USD, but ultimately it is the US military that backs up the 'reserve status' of the USD. This is because the strongest economy in the world also needs a strong military to protect it, thereby ensuring stability and hence investor confidence.
But yes, it can be argued that much of the US military budget is wasteful spending. It could be cut 3-4x and still be the largest military budget in the world.
Here are the numbers:
US GDP is $17 Trillion
http://research.stlouisfed.org/publications/net/page24.pdfUS M2 is $10 Trillion
http://www.federalreserve.gov/releases/h6/current/h6.htmUS M3 isn't published anymore.
US Military budget is about $670 Billion.
http://en.wikipedia.org/wiki/2013_United_States_federal_budgetMilitary/GDP = 3.9%
Military/M2 = 6.7%
If we extrapolate this to bitcoin, we have 21M*.039 = 819,000 and 21M*.067 = 1.4M.
If the right number is around 1 million, then divide that by 365 days, 24 hours, and 6 blocks per hour we have 19BTC per block reward.
At .0001 BTC fee per average transaction thats 19,000 transactions a minute or 320 transactions a second. But, in the future transaction fees will likely be 100 times smaller, so that would require 3,200 transactions a second to keep up with US military spending. This is basically impossible from a technical perspective without major changes to bitcoin.
Perhaps a comparison to M3 would make more sense, the numbers aren't publicly anymore.