Because they don't think it applies to them. When teaching, these issues arose. They would sit there and listen/watch films etc. and I'm certain that some had switched off. There was a girl, think her name was Hannah Betts (I may be wrong, it was a long time ago) who died after taking 'E'. Her parents funded a very clear, graphic, moving video which pulled no punches and would make you cry. Having shown it and got the usual 'yeah' responses from some quarters, the only way I really got through was to cite a kid who had died not 5 miles away and to tell them straight that the only reason I had bothered to get hold of the video for them was that I rather liked them and wanted them to be alive in 10 years time.....I then asked them how many would be alive then and there was a silence as they left. I hope it did some good, but it takes something like that to bring a personal relevance. Shock them by applying it to them is the only way, but you can't always be there.
One moment of stupidity and there is so much devastation and waste.