1700 words per day to reach 50,000 words in a month,
I was referring to this 50k per month, which is still a lot.
Your post has ~500 words and I am sure you've spent some time with it. It's not different with writing fiction I guess. It just consumes a lot of time and that thins out potential participants, although NaNoWriMo is surely great for people with the necessary time and muse.
It's possible. I've seen quite a number of people take up projects like this and even over shoot it.
I know someone who writes s about 5000 words everyday. It's difficult, yeah! But, it's achievable nonetheless.