It’s called keeping up with the Joneses. Pretty much everyone knows that idiom. Using the success of another person as a benchmark for your own.
You are you. You cannot be anyone else but you… well you can be someone else, but the last time I checked Hand That Rocks the Cradle and Single White Female were horror/thriller movies. 😛
Yes, there are bestseller lists everywhere. Yes, agents and publishers want to know whose books resemble yours so they can market yours better. That’s business comparison. I’m talking about comparing your writing speed, the amount of books you put out, how much you promote, your presence on social networks, etc…
You’ll drive yourself nuts if you continue to always set your goals based on the person next to you. Know yourself and set your goals accordingly. Don’t compare the sales of your book to the sales of a book that released the same day and from the same publisher. Instead, compare the sales of this book to the books you’ve released in the past. Are the sales better? Worse? What did you do different? What could you do different? What needs to stay the same?
Just because Author A can write a full length novel in a month doesn’t mean you need to stress yourself out — and possibly burn yourself out — trying to do the same (NaNoWriMo excluded from that, though that’s only once a year).
Everyone’s situation is different. Some people are full time writers while others have a day job and can only write part time. The sooner you come to terms with what you can and cannot do, the sooner you can set more realistic goals to help you improve.