I was just looking through some past transactions.
In December of 2015, I bought a kind of fancy litter box (you clean it by rolling it over and back, depositing the filth in a removable tray) for the cats, using Bitcoin. It came to $28.19.
As of a few minutes ago, the amount of Bitcoin I paid for it was worth $3,563.98.
If I had spent the Bitcoin at the price I bought it at, that would be a missed ROI of 12,542.71% in six years -- an annualized ROI of 123.73%. Of course, I actually spent it at a higher price than I bought it at. And I did OK. But if I had to choose, I guess I would rather have $3.5k than the damn litter box.