It sounds better loud in a car. Think about your favorite band playing music quietly at a concert or blasting it. Which would you find more appealing?
It is also a way to attract attention from a bystander. You're blasting Ratatat you stop at a stoplight. A girl hears and sees you playing it. She smiles. You smile. You decide you want some coffee. You pull over and go into the coffee shop. She is in there. She mentions she heard you playing Ratatat. You strike up a conversation. 2 months later youre dating. 1 year later your engaged. 5 years later you're married w one in the oven. All because you were blasting music 6 years and 2 months ago.
I blast music btw in my car. The latter example provided might be common with being a young age and misplaced priorities such as not being cognissant of the fact you're wasting electricity. Or maybe they want someone to believe they're in their room.
In the end what does it all matter? Were all just cogs in the machine.