It’s not like running a marathon: it’s like aiming to walk 26 miles whilst wheezing asthmatically. And then admitting you’ll only manage 14.

Why not set yourself the target of 8,000 good words, and have a useful finished product? It need not be for a deadline or to be published, but just the personal satisfaction you seek from doing 50,000.

Doing NaNoWriMo to improve your writing is like running ten miles a day to practise for a fencing competition. Yes, you’ll be fitter and yes, your fencing will probably improve as a result, but there are better ways to spend your already-packed time if you wish to improve your swordplay.

If all you seek is enjoyment, then I can’t come up with a viable objection. But you can’t accomplish anything in a project for which you have no expectations.