USD has a lot more going for it than bitcoin.

Pros to USD
USD: untraceable transactions via physically exchanging cash
Bitcoin: traceable, all transactions recorded on blockchain

USD: Keep cash in an FDIC insured bank account and the government is good for the first $100,000, fraud/theft protection
Bitcoin: 15% of all coins currently held in circulation were stolen from their original owners (if you believe the list of bitcoin thefts on this forum)

USD: zero transaction fees for cash or check deposits or withdrawals, or ACH transfers
Bitcoin: transaction fees

USD: treated as cash by the IRS, duh
Bitcoin: treated as a commodity by the IRS, taxed as capital gains

USD: costs you nothing to safely stash it in a FDIC guaranteed bank, and you get paid interest to boot!
Bitcoin: spend lots of your money for security, you're in charge of it yourself

USD: exchange rate is very stable, intrinsic value is its guarantee as a medium of exchange by the U.S. government & use as a medium of exchange by U.S. economy, and the U.S. government and U.S. economy are powerful entities
Bitcoin: exchange rate is extremely unstable, has virtually no intrinsic value at all (compare to money orders)

USD: currency exchanges are stable, reliable, no risk of theft
Bitcoin: exchanges are unstable, unreliable, risk of theft

USD: can keep a bunch of them of varying types in wallet easily as paper medium
Bitcoin: poor/zero implementation as paper medium

USD: inflation rate in the near-term (1-2 years) is very predictable, and long-term inflation is quite low.
Bitcoin: deflation rate as measured by bitcoin's exchange rate is very high, making it unattractive as a currency and instead attractive as a commodity/hedge against the dollar (probably why the IRS pwned bitcoin by treating it as such)

USD: I can make a bunch of cash transactions under $5,000 and it's not recorded anywhere
Bitcoin: I can make a bunch of transactions and every single one of them is viewable by everyone in a global database.  NSA's wet dream, how ironic.