Why are some dealership guys absolute douchebags?

I consider myself a "car guy" but I find a lot of guys in my local scene who are more "connected" to dealership owners (ex; son of a dealership manager) are absolutely dickheads. Like I have a car I can afford and I fixed it because I enjoy fixing cars, but because it's at 180,000km (even though its in an amazing state for its age) people from dealerships still look down on me? Why is that, why do they act like they know everything, and then blatantly say some of the most corny things imaginable (4th gen soarer stock could gap an n54 335i tuned, anything past 100,000 km is a death sentence for any car, bragging about selling local car club people cars, etc.) It'd be one thing if they had real info to back up what they say, but they mostly brag about being "stage 3 tuned" without explaining what they did to their car.