Why did bitcoin soar to a record this week? Fans of the world’s largest cryptocurrency say it is due to old-fashioned laws of supply and demand.

Like the price of any commodity—whether it be gold, oil or soybeans—bitcoin’s price is sensitive to fluctuations in demand. And demand for bitcoin surged after the January launch of US exchange-traded funds, known as “spot” bitcoin ETFs, that directly hold units of the digital currency. Since then, investors have poured billions of dollars into these ETFs. Those inflows prompted the funds to buy bitcoin to meet the demand, bidding up the price.