Is there anything that wasn't made out of thin air, everything once had no value until it got adopted and became useful. Bitcoin is a currency that can be used as an alternative to fiats and that's why you should buy it. It mightn't be useful today but it does have a future as developers are working on its utility everyday. Bitcoin isn't been used globally as a currency because it's undergoing attacks from the government as they can't control it.

Have you done some research on Bitcoin, if you haven't then you should as that's when you'll understand what Bitcoin. Don't invest when you don't understand what bitcoin is, for now it's used as an asset but that's not its only used. Bitcoin can be used for fast , secure transactions.