You might as well say mining is an addition then as well. At the prices some of the devices are going (USB block eruptors anyone?) a lot of people are likely wasting money instead of making it.
At the current prices, even USB eruptors ROI/make money. Correct me if I'm wrong.
Assuming a fairly low difficulty increase of 80%/month a block eruptor would make like $17 if it started mining today. Best prices on ebay are around $50. Well, assuming BTC hits like 3.5k it will break even. In which case it would have been better just buying bitcoins ...