Bitcoin’s supply is limited to 21 million (really like 16-17million due to lost wallets and Satoshi’s holdings), making it scarce. As more people want it and adoption grows, its value increases + factor in that it’s seen as a hedge against inflation because its supply can’t be increased like regular money. The “yield” comes from its price rising over time, not from earning interest or dividends. You profit as the masses adopt it and the price goes up.