Everyone who trains Brazilian Jiu Jitsu has their own personal reasons for starting in the "gentle art". Some do it for exercise, others for self-defense and some enjoy the competition found within BJJ.
Now there's no way to make a blanket statement about how comparison impacts ones training. Some use it to push themselves to the next level while others can self-sabotage their Jiu Jitsu journey with this common double-edge sword.
As a black belt I have seen some high-level athletes and even some "regular Joes" feed off of the benefits of comparing and competing, this article is not for them. Instead I'd like to speak to those of us that gauge our growth and successes off of how well others are performing.
Maybe it's a student that started when you did, or a similar ranked student that came from another school, but every time you see them perform well you begin to question where you're at within your own journey. Another strong example is when teammates compete and do well. Now you have this made-up pressure on your shoulders to match their results. Again I am not saying this type of comparing can't be healthy for some, I'm just saying it may not be the best approach for everyone (even some of you that love competing).
Comparison will always come with it's fair amount of pressure. This pressure is a huge reason why some students don't make it past their white belt. You probably said something like "My teammates performed well, I train with them and trained like them so I should match their results, if not do even better!". Then competition day arrives and you bomb, or maybe just fall short of what you thought was a "sure thing", regardless of the result if it was anything less than you expected you suddenly feel like you let your team down, or disappointed your coaches. That unreasonable feeling can cause you to avoid training for a few days, maybe those few days turn into a few weeks. Justifying in your mind that the more time that passes, the more people at your school will forget your results.
This common example is just a small look into the many ways comparison can not only effect you mentally, but take you away from Jiu Jitsu entirely. Teddy Roosevelt once said "comparison is the thief of joy". That quote hit really close to home with me as a beginner, and helped me gauge my growth in a healthier way.
At the end of the day Jiu Jitsu has to fulfill a need you have, don't let the progress of others determine your growth and stopping you from getting what you want out of training Brazilian Jiu JItsu.