If nothing else, the price of bitcoin since 2013 is enough reason for one to regret if he is not holding even 0.1btc in his wallet, whether mistakenly or as an intentional act. Since 2013 till now, the price of bitcoin has done more than 1000% and more to come.
If you knew that long ago, you shouldn't be too late to enter this forum so you can see and discover more new things about Bitcoin through this forum. But that is not a problem for anyone, because when someone knows about this now, at least there is a special consideration for continuing to own Bitcoin and buying it gradually without the slightest doubt. Moreover, the evidence is also very clear that Bitcoin can increase a lot after more and more people start to like it like now.