My thoughts as someone who is 26 and has tried to get every single one of his friends hooked on skiing and why it has mostly failed.
1- Instant gratification. Its hard to be a good slalom skier. You simply cannot be athletic and be a good skier. As everyone here knows its a technical sport and just being big and fast doesn't help. The best skiers are the ones who spend the most time training.
2- Price. I will go to my grave saying this. Its too damn expensive. If I want to start any other sport the barrier to entry is less than $1000 to start unless you start messing with horses. If I want a friend to start skiing I can point them to SIA, they can use my boat and I won't even charge for gas most of the time. Still a used ski, bindings, vest, handle, gloves will run them damn near if not more than $1000. Even people I skied with in college for 2 years were hesitant to spend the money on their own equipment, understandably so.
3- All of our friends have surf boats. We go with them see something that is super simple (i.e. instant gratification) and you can drink while your doing it. The number of times I've seen or been thrown a beer while surfing.... Cant do that in a slalom course.
4- For people who don't get it, watching a good skier is not as impressive as they realize. I took a friend to the lake this summer. He watched me get a couple at 32 off 36 mph straight up. Nothing amazing but not terrible. We were with some friends the other day and he told me if I gave him 1 summer he would be able to beat that. A short, should we call it a debate, followed. I explained it takes years to be able to run even into 32 off. He didn't believe me, still thinks 1 summer is all he needs. He isn't a skier. I remember listening to the 2008 worlds video cast and Marcus Brown made a point when Rossi was skiing. He said "the better the skier the less impressive it is to watch because they make it look easy" I 100% believe that and sadly the spray can be the coolest part someone sees.