Professional athletes, along with most people who work out 4+ days / week, have their own more advanced/expensive ways of determining their own personal weight

Professional athletes, along with most people who work out 4+ days / week, have their own more advanced/expensive ways of determining their own personal weight and judging where they should be, factoring other measurements like muscle mass percentage. They also make up a very small percentage of the US population. For everyone else, it's a decent approximation of weight. As anecdata - I'm on the opposite end of the physical activity spectrum to Tom Brady, I'm also 6'4" and the heaviest I've been is about ~210 lbs. I was definitely starting to feel "a bit too big" at that, and would confidently say I'd feel overweight at 225 lbs, so the scale doesn't feel massively miscalibrated to me.