So if I flip burgers and buy BTC, I'm indirectly mining BTC? (Minimum wage paycheck) => (BTC), voila?
Some twisted thinking, but K.
The vast majority of altcoins don't even have altcoin X / USD pairs. You are forced through BTC first to cash them out. It's not that big of a step, or so twisted.
Apart from Ether - you can trade it against USD on BTC-e, Kraken, and now Gemini. These exchanges are hedging their bets in case bitcoin fails. All we need now is for Coinbase to join them and we have full house.