For speculation? To buy on the dark web? To buy online on sites like purse.io? To send money? To do business? To have your money under your control?
What is/are your purposes when yu buy bitcoin?
Bitcoin is one type of investment which we can make profit through trading, where as in fiat we can do trading but it's two risky when compared to bitcoin.I am not investing all my money into bitcoin just a spare money which will make me some more money from it with the knowledge i have.