This billionaire's Bitcoin investment plan follows a solid fundamental approach to buying volatile assets. The price of Bitcoin (BTC 0.66%) is primarily determined by the law of supply and demand. Since there's a fixed supply of the cryptocurrency, growing demand will lead to a higher price. And demand could be increasing due to a big new buyer. Jack Dorsey, the CEO of fintech Block (SQ -2.58%), devoted his entire first-quarter letter to shareholders to talk about Bitcoin. Among his comments, he noted Block ...