One reasons teens use drugs is because they like them, take beer for example, a lot more teens drink beer than adults because they like it but this can lead to them abusing the drug which can lead to death.
Another reason teens use drugs is because they think it is 'cool' but in reality, the drugs are not cold, the environment is. Using drugs to be popular won't help, you won't know if your popular if your dead.
Another reason they use drugs is because they have been through tough times and need something to distract them but seriously, there are better alternatives, for example, binge watching T.V.
Lastly, the ads, the amount of beer ads that show people drinking beer having fun just to advertise it is definitely something, but why would you believe ads, most of them are misleading.