I think it's a age thing that has a different material focus with each generation. In my youth, it was the acceptance of junk food, - mainly due to the post-war influx of US culture and it's glamourisation in pop music and TV. There was little consideration of the food values of burgers, pizzas, noodles, confectionery and sugary drinks. That coupled with the general teen attitude that parent's advice was of another age and as such was to be rebelled against. Then there was the seeds of their addiction to motorcycles (including scooters) and cars in movies where teenagers, probably of middle-class parents, drove around in large cars as essential parts of their social development and 'becoming adults'. This was in an age where the annual road death toll exceeded 8000! Essentially, until they had experienced some of the negative aspects of adolscence, advice and warnings from mature adults were unwelcome and duly ignored.
Fortunately, a significant proportion of baby boomers have witnessed significant damage done by and to their children and now their grandchildren that they see the need for premanent change of culture in respect of health and the environment.