This just all depends on what circle you're using the word "hacking" in. While technical circles are mostly concerned about the technical details on how someone might exploit a system, legal circles don't really care. They usually avoid using the word "hacking" anyway.
The relevant law here, the CFAA, is often referred to as the US law that criminalizes "hacking", but what it specifically does is criminalize anyone who "intentionally accesses a computer without authorization or exceeds authorized access" which is much more broad than how technical disciplines might use the word.
So yes, stealing a password off a friend's post-it note and Hasselhoffing their instagram might not be considered "hacking" if you're hanging out at Defcon, this would be considered "hacking" in legal or colloquial terms.
The relevant law here, the CFAA, is often referred to as the US law that criminalizes "hacking", but what it specifically does is criminalize anyone who "intentionally accesses a computer without authorization or exceeds authorized access" which is much more broad than how technical disciplines might use the word.
So yes, stealing a password off a friend's post-it note and Hasselhoffing their instagram might not be considered "hacking" if you're hanging out at Defcon, this would be considered "hacking" in legal or colloquial terms.