Writing is one of the loneliest jobs in the world, not only are you likely sitting at home alone in a closed room, but when written correctly your work looks easy, and trying to explain to someone that making a piece of writing seem simple and easy is a great deal of work is an effort in futility and one that no one really wants to hear, so just as doctors and lawyers and all types of artists seek out those who understand their profession writers must do so as well. But, it is not only for this loneliness that writers should seek out the company of others who understand his craft, but for the help in improving the craft that can only be achieved by those who understand what you did, no one can help with creativity as much as those who are themselves creative, and of course there are business advantages as well.
Most writers like the solitary nature of the writing to some extent or another. Being alone with your thoughts can be a gratifying experience, just as working in your bathrobe and slippers and drinking cold coffee can be a great day, but you can't live forever on yesterdays pizza and mountain dew and at some point you need to see other people. For most people this is not an option, but for many writers the ability to become a hermit is possible and so a weekly writers group or just a cup of coffee once or twice a week is an good way of seeing a fresh group of faces.
Years ago I spoke of writing occasionally to people who are not writers. The time I remember most vividly was when i went to lunch with a good friend who asked about the story i was working on. I know he was a good friend because he didn't interrupt me during the next fifteen minutes when I explained to him why I had decided to use an unreliable first person narrative in the story rather than the more traditional storytelling techniques and how pleased I was that it had worked.
When I stopped indulging my ego and looked at him the blank look on his face reminded me that he probably had no idea any of that really meant and so I apologized and asked him about school. It was at that moment that I fully understood that people who aren't writers who ask about your work are being polite and really don't care. On the other hand that same conversation with someone who spent as much time writing as I did would likely have been productive and he might have even given me some new ideas or told me why my writing plan was stupid.
Almost all of the best ideas I have come up with have been improved when I was telling my friends about it. It might be a small question they ask, or a flourish of the story I add to try to impress them as I am speaking or the simply a sudden realization of the meaning of part of the story but those flashes almost always come best when I am with people who are also creative. They ask questions or even toss in small ideas that sometimes I use and sometimes I don't but that always inform my stories. It is easy to fall into a creative rut and allow your work to become like a job and one of the best ways for you to avoid that is to be around people who break those thought routines.
The final, and most cynical reason to spend time around other writers is because of the business of writing. We would all like to believe that every novel ever published was published purely because of the skill and talent of the writer but we know that isn't true and being friends with someone who happens to know someone is often the push our story needs to reach the correct desk. So long as this isn't the only reason that you spend time with these people there is nothing wrong with the understanding that it could help your career just as your success someday may help theirs.
No matter your personal situation or goals in writing spending time with other writers is a enriching experience that can improve both your writing and your life in ways that you wouldn't expect and for anyone who isn't in a writers group I would strongly suggest you go to your local library or university and locate one.