Why do people come off sertraline?

If you have high blood pressure or high cholesterol you are on tables for life.

I note a number of people on here 'coming off'  sertraline when anxiety is probably with you for life.

Is it so bad to take a tablet a day to feel great? or is their long term side effects? 

Can’t speak for other people but maybe they find the sertraline doesn’t work for them anymore, maybe they think they can do without it now. Who knows? I know I plan on taking mine for a long time because it has helped me greatly. 

Sometimes people has side effects that they do want to get rid of or feel they are healed???

I took zoloft few years ago with succes for 4 years. Now, I have a pretty hard time even at low dose.

Sertraline 100 mg has worked very well for me.  I was advised by my psychologist that staying on it long-term would be good for me. I know some people don't want to take meds for a long time, or they start feeling great and then don't want to take it anymore.  For me, I know how I am without it and I do not feel that it would be a wise choice to taper off.  One thing I wasn't all that thrilled about was weight gain I've had but it seems to have leveled off.  

At what dose did weight gain start?

50 mg.  It was pretty much immediate for me.