Trying things out helps you decide if they're right for you. But it's also human nature to avoid things that are obviously bad for you. Like, you wouldn't experiment with jumping off the Brooklyn Bridge. Or getting a pet rattlesnake. Or piercing your, well, you get it.
Most illegal drugs are always bad.
There's no good use for sniffing glue or snorting heroin. But many drugs were developed as medications by doctors to help treat patients with very specific medical conditions. And for those people, drugs make sense. Unfortunately, many of these drugs are used by people who don't need them. Which, if you think about it, is kind of like going for chemotherapy when you don't have cancer.