Yes, but sometimes external pressure helps, as well as a deadline that's not self-imposed. I'm personally using it as a chance to experiment, and to see if I'm capable of writing that much with a deadline. There's also the social aspect of it, much like Movember, etc.
I did the last 3 NaNoWriMo's but never finished 50,000 words in the month. Work, school, raising kids, etc. However, it did get me started on 3 novels. One is a kids fantasy novel I lost after getting 6 chapters in (though I still remember the basic plot). I remember I got stuck on that one because I didn't know exactly where to go after chapter 6. One that has 3 chapters fully written with the basic plot, plot twist, and ending idea that I intend to get back to later. The 3rd one I am still actively working at least once a month. Plot and outline are completed, all events mapped out with timeline, all chapters have a short synopsis written, and 2 chapters are fully completed.
It sounds like the 3rd one is the least complete of all, but actually the reverse is true. I found that without having more than the basic plot, I got stuck on the first one because I wrote myself into a situation where I didn't know where to take the story next. The 2nd one, though it has fewer chapters than the first, is actually further along because I knew the beginning, the plot twist, and the end. But I didn't have all the events in mind, no timeline of those events, and no synopsis of each chapter. So while I know the beginning, middle, and end; I got stuck about 5000 words into it. I'm 5700 word into the 3rd one with no stumbling blocks in my way. I'm just filling in the structure with the actual words now and focusing more on dialogue instead of "what comes next".
Whether you finish or not, and whether it is a great story or not is irrelevant. The important part is making the effort. Even if you throw away your first attempt, the more you try, the more likely you will come up with something that you think deserves to be finished and hopefully published. Also, check up on the website for group meetings in your area. I attended a couple and had a pretty good time meeting other NaNoWriMoNuts.
