Bitcoin is a commodity - not a currency.
It was designed to be electronic cash, but with high fees doesn't look like it anymore.
You go ahead and throw your money away... you'll get 4% interest a day, but you'll never see that money.
Freebitco.in already existed when I started Bitcoin, it's a faucet/casino with high house edge. As far as I know, the 4% is legit. I think it's just a very cheap way for them to increase their bankroll.
In the past year forks and airdrops have been worth much more than 4% though.
I'm using the wrong account.