Quick note, saying that "because you're autistic peer pressure doesn't work on you" is largely true, but there is a flip side to that, in that once an autistic person give in to something they can become monomaniacal about the thing they got into.
Most of the time, this just means that they develop a very deep understanding and fondness for things like vacuum cleaners or B grade horror movies or whatever happens to be the thing that latches on for them. But on the other hand if the thing they pick is unhealthy, this monomania is a recipe for going off the deep end.
I have a couple friends who are on the spectrum and one of them went really off the deep end with drugs and ended up getting into heroin.
We all tried to put a stop to it but they would not listen to our "healthy" peer pressure. It took another one of our friends who had also gotten into heroin ODing and dying in his bathtub to snap him out of it.
I said all of that to say that if your friends begin to caution you that they think a behavior of yours is unhealthy, step back and give them the benefit of the doubt and really evaluate what you're doing and what they're saying.
It could save your life or prevent it from becoming dramatically worse in some way.