That's not entirely the case why bitcoin is created although many people did think that bitcoin id created to replace bitcoin but it isn't true. You can say that it is an alternative to fiat where no third party or a government for example is behind it. In my opinion why many people are investing in bitcoin is because many people make it as an investment opportunity when it's uses isn't actually for investment but since bitcoin's volatility then people use that volatility for a chance to earn profit hence why many people invested in bitcoin.