I dont say hello to pretty much everyone i pass when on the road bike, not beacuse im a miserable sod (well i am but…) i can pass 30+ people on a ride and ive got headphones in so i cant be arsed to say hello to everyone i pass, im very much a head down and concentrating on my road ride kinda person
Plus i like riding the road bike to get away from people so i dont have to interact with anyone, also i dont do cafe stops (much to the horror of any roadies i do actually speak to when im not on the bike) i dont like coffee and im on the road bike to help lose/maintain weight so why would i stop to fatten up!
MTB is completley different, its more of a social thing for me, having fun and catching up with mates, i tend to pass less people and im going at a slower pace so a bit more inclined to say hello and interact with people walking/riding when they make space for me to pass