That's the biggest lies pirates say all the time, hacking the console itself is against the DMCA (USA):
https://en.m.wikipedia.org/wiki/Digital_Millennium_Copyright_Act
The "you own the hardware and you do what you want with it" is complete BS, the fact that no one has been prosecuted doesn't make it legal.
What if someone sold you a gun that was used to kill someone without you even knowing someone else was killed with it?
What if someone sold you a car that was used to ran someone else over without you knowing?
What if you bought an Ipad an turned out to be stolen? You might still get in trouble.
Of course this are highly exagerated examples but you might still be liable by having something ilegal in your possesion... Being ignorant of the laws doesn't exclude you from following them, but again no one has ever comvicted by hacking a videogame system.