_ Emotional control: one of the most difficult thing is controlling your emotions while you watch your assets fluctuates greatly, mostly if it's going down, without you pulling the plug out of fear, so i believe it's one of the key they have.
Great point but I think you are wrong, most bitcoin millionaires I know didn't invest in bitcoin., and sat by it watching the price go up and down, if they ever did that, they probably would sell out of fear of losing their money..
Most people who became or have become millionaires through crypto and bitcoin investment I know of invested, and then, left it and focused on other important things in their live, this move helped them to forget about the investment, allowing it to grow to the fullest amassing lots of profit.
So trust me, if you invest in bitcoin and sit by and watch it go up and down in price, you most likely will end up selling it too early, so the best way to hold is, focus on other things and forget about the coin.