I don't understand that. I really don't.

If you're curious, getting drunk or otherwise modifying your mental state with alcohol or drugs is an "experience." It's like a small adventure contained within your person. The world looks and feels different. I don't recommend it but that's the appeal of being drunk or high or going on a trip when you aren't an addict or using it as a bad way to treat mental illness. Lots of people have curiosity about how altered states feel, or know they enjoy it from previous experience.