Because in the context we're discussing, it's an escape.
Sure, tiny amounts of cocaine act as a stimulant similar to caffeine. Coca tea is just fine and safe.
But a nose full of cocaine is way, way, way more drug than the tea contains, and makes you feel REALLY good for short while. Almost every single user ends up binging every last bit of cocaine they have on them, and staying up all night.
They do it because of the reward system it kicks off in your brain.
Will they end up chronically addicted to it? Not everyone, but the thing is, it has little to do with willpower, knowledge,or strength. Statistically some people can walk away... but you have know way of knowing if YOU are the person who can walk away. You might think you are, but that's meaningless. (And the thought that you can walk away leads to "Well hey, why not tomorrow night too? After all, I can obviously walk away!")
The same pattern repeats, more or less, for most habit-forming drugs - tobacco included. Alcohol actually ranks quite low on this scale, though it's far more damaging than many illegal drugs.
So back to the original question - why do people think it's an escape? Because it generally is - people do it to experience a different reality than their own, and personal risk. That's not necessarily bad, but it IS an escape... just like many other activities, like snowboarding or skydiving.... it just has a much higher risk factor.
So clearly we should poison everyone's coffee with lead. We have lots of our fellow citizens hopelessly addicted to this terrible substance. They cannot function without it. Clearly the only way out is to poison the coffee.
Then, while we are at it, let's add some mercury to cigarettes, and put maybe put arsenic in fast food hamburgers.
Some may see it as enhancement. Besides, not everyone shares the same motives.