I mean its the SAFE thing to do, but realistically its not a massive issue to worry about. Ive build 5ish computers on carpet without one and i have yet to fry anything, i just try to touch something meta(case or psu)l every once in a while and i generally dont wear socks. Not wearing an anti-static wrist-strap is kinda like driving a car without airbags, youll be already unless you get unlucky (and then your screwed )