It's always annoying when a friend develops an annoying habit...this can be just constantly chasing men, looking down on people, being generally rude.....goodness, it can be anything, but it's worth having a chat about it and the reasons why.
If she's insistent that she wants to continue doing Coke then that'll suggest your values change and you might drift apart. If the friendship is worth it, make the effort when she's not doing it, so you can continue to enjoy your relationship.
Re: the Coke/drugs V alcohol debate...it's a very aggravating conversation to have. Whilst alcohol is addictive and causes huge social problems, many people drink occasionally, and other than a sore head the next have no lasting problems or dependency! I've been drinking for years and have never committed a crime, been involved with police, had a fight, left myself in a vulnerable position, or caused any problems for others...not always the case. I just have a giggle and boogie, and then get some chips and go home 😇
I know a pothead who proclaim that there's nothing wrong with cannabis and/or drugs yet cannot see that they have turned into a horrible, volatile aggressive individual who cannot deal with real life emotions as he's usually stoned, and now struggles with depression and mental health problems...but it's definitely not the drugs that caused it 😳
Each to their own really, and despite the substance, it's all down to the individual and how they are using it.