Riders are free to ride how they wish.

I don't want anyone to do anything stupid or get hurt. I generally state just that before a race. I won't lecture people, as you suggested.

I know individuals who I feel do ride poorly and dangerously. I don't like to see them at my races becaue they make street riders look bad. I deal with them as individuals. If they had a history of injuring others I'd probably ask them not to ride. I don't generalize their behavior on the entire population. Generalization is part of the problem, not the solution.

I don't feel that winning a new messenger bag is worth possibly killing myself or injuring someone else. Others may feel differently. I probably won't like them and I wouldn't want to ride with them. At a race I'd make sure I stayed away from them. Maybe I'd imagine them as an H3 with a really tight turning radius. Most likely I'd forget about them and try not to get hit by something that can cause me much more damage.

Most of the races I've been to are won by the most skilled people. People who race dangerously for mid-pack placement don't need to be in a race to ride like that. I see them riding poorly every day all over town. The race just happens to be where they are riding poorly at the moment.

All that said, many preventable race accidents I've seen happen when smart, skilled people do something stupid. There's no way to prevent something like that.