Frankly speaking this ROI is really vague. I mean for an ordinary person or even an extra ordinary person there was no way to actually buy bitcoins from someone until 2011-2012. Bitcoin users were pretty much isolated and most of the trade took place on this forum itself. Moreover as you have mentioned the insane ROI in the upward sense. Allow me to mention the ROI in negative sense too. Imagine those who bought BTC at 19k and sold at 3k. It's certainly a 70% loss which not many stocks suffer everyday. and yes before you say that those people are idiots who bought at 19k and sold at 3k. I really would call even those people idiots who bought bitcoin in 2010. They were just lucky enough that they bought it.