There was one who lived over the road from me a few years back who would rev his broken exhaust bike at 5am and wake everyone up. About three weeks later his motorcycle mysteriously caught fire in the early evening. There were people smirking out of their windows enjoying the schadenfreude. There’s still a puddle of aluminium melted into the ground where it died.
It's a lot like rolling coal[1]. No actual safety purpose, people do it simply to project insecurity and irritate others. Sometimes I think society is too tolerant of purely antisocial behavior, but I guess in the US everyone has the freedom to be a donkey.
Obviously higher speeds=higher wind noise; you might be fine < 35mph (~ 55kmh) in a city, but anything above that hearing protection is advisable.
"Measurements of motorcycle riding noise levels vary, but are generally around 85-95 dB at speeds up to 35 mph, climbing to 110-116 dB at 65 mph"
I used to like the sound of engines, still do, but I never understood the farty exhaust tbh.