I can prove that not a single person has traded optimally the past couple of years.
The optimal strategy for my join date of June 2011 would have been to buy at $2 in Nov 2011, sell at $266, rebuy at $50, and sell at $165. If so, an initial investment would return 43,900% ROI. If you'd bought $100 worth of bitcoins at $0.01 and sold at $32, in addition to the above, you'd theoretically have $140,448,000, but in reality you'd have put a damper on both the rallies and the crashes and would "only" have around $50 million. Since the peaks and valleys weren't dampened, we can conclude, and draw comfort from, the fact that not a single solitary person has traded optimally in the past two years. QED.
Compare that to the traditional world of investing, where in the best of all possible years to start investing for retirement vs. year to withdraw for retirement, this NYtimes graph shows that 8.4% annual return was the best possible return since the investing class of 1920:
https://www.nytimes.com/interactive/2011/01/02/business/20110102-metrics-graphic.html8.4%/year for 20 years is about
500% ROI, which you'd get if you invested in bitcoin anytime before February 1 2013, and sold now @$100.
Bitcoin has actually functioned as a damn good savings account. Sure, not everyone can "retire" at once, so to speak, but for those that have needed to cash out their coins, they've been able to do so at >$100 most of the past month. That's really quite impressive.