So,
1) If they hacked into my machine and stole the private key; (illegal)
2) If they sniped the pk while snooping on a public access connection; (illegal)
3) If they brute forced the private key into existence; (not illegal)
4) If they snapped a shot of my private key qr code over my shoulder at an ATM. (not illegal)
What if I claimed an address on the block chain with a signature and 3 or 4 happened? Would I have a case then?
If 3) happens then
all Bitcoins become worthless and the question would become: If I take something which is worth nothing is it illegal?
Well I guess you could argue that even though all Bitcoins are now worthless they still might have sentimental value.
Haha well I doubt we'll get there anytime soon s don't you worry

you just keep on HODLing.
It is illegal to steal digital goods. It's a fact. But to others' points, the authorities will most likely do nothing or start a haphazard investigation and in the end getting your $500 back from a hacker off the coast of Taiwan won't be a priority. Giving those punk kids their $150 speeding tickets will meet the quota nicely