I can see where you coming from especially with your friends changing; though personally, if you friends and family start to see changes in you while when using it, you either need to stop like you were implying, or learn to control your usage. I've been smoking instead of taking prescripts for years now, and honestly ask a few of my friends, they always have told me I haven't changed since HS, yet they don't know I smoke either.
I will not let being high become a problem for me, honestly I start to see a potential negative side to my actions or how I feel, I just take a break and cut back. I don't think a drug should ever change who you are, just enhance how you live, just never let it become a problem.
I know not everyone has I mindset like I do, but I really don't ever see me quitting because it's honestly how I get most of my work done, and most of the time it's better quality than If I did the same job sober, I know it's not that way for everyone, but it is for me.