There are two basic ways to try to make money "investing". You buy a productive asset because you can get it for less than it is worth based on its future cash flows, or you speculate on a product because you believe the price will increase in the future. Most major markets have both (stocks, real estate, etc). Commodities and currencies are only speculative because they don't generate cash flow. All speculative "investing" requires that someone else pay more for it in the future, thus relying on the "greater fool" theory you bring up. I can't say if BTC will be worth more or less in the future, so I don't invest in it. I prefer to invest in real estate or companies that generate cash flow so that I can much better predict their value. A USD or a Bitcoin have no intrinsic value, so it is impossible to know what is a good price to pay. We know now that $60,000 for BTC was too much only because it crashed. Is $20,000 a good price or too much? Only time will tell. It's much easier to get rich with something more predictable like real estate, in my opinion.