If you bought in June of 2011, at the worst possible time...

[chiropteran]

If you bought $10,000 worth of bitcoins at the peak before the crash of 2011, your investment would be worth double that today, approximately $20,000.

So, if you buy something, and 21 months later it is worth double what you paid for it, did you really fall victim to a bubble?  If so, I welcome further bubbles!  Bring on the bubbles!  I'd love to double my investment every 21 months!

[Amitabh S]

What if it became double in 1 month? as it happened recently?

[phlogistonq]

Exactly this happened to me, except that I only bought 2 BTC, at a price of Eur 25,- each. Never sold them, and glad I didn't.

[Wekkel]

Today, I looked at my tiny mining payments of 2011/2012. A lot of money today, but nothing at that time. I keep on repeating everywhere: Buy and Hold.