Did anyone validate this chart? It is using 31st Dec prices for each year?
Just bet if you picked the highest price in each year to buy and the lowest in the later year to sell could come up with a very different conclusion.
To date - timing is everything...
If anyone could reliably, continuously market time they'd be a billionaire. The reverse is also true, if you picked the lowest price of anything one year and sold the highest the following year, you'd be rich.
The point of the chart seems to be: if you bought (or mined) and held for any reasonable period of time you'd have done well. If you try and trade, all bets are off.