If I ask you to give me a loan and I say I'll pay it back with 100% interest in a few days, and then I run away with your loan and never pay it back, then yes,

If I ask you to give me a loan and I say I'll pay it back with 100% interest in a few days, and then I run away with your loan and never pay it back, then yes, it's stealing. That's all that's happening here, except in units of BTC and not USD...