The redoubtable Rob (in Denver) Siders suggested in the Comment trail that I ought to hie myself over to 101 Reasons to Stop Writing, and I, being highly suggestible and having other things I ought to be attending to, immediately did so.
It's a pretty funny site, in a gallows-humor sort of way. The Reasons themselves are a work-in-progress (only 16 of them when I visited), but they are an equal-opportunity snarkfest, heaping opprobrium on writers published and unpublished alike. There is also a wonderfully misinformative On This Day section, a hilarious set of Demotivator Posters ("GENEROSITY: Don't give copies of your book to your friends or family. You'll halve your market."), and a fine WebStore selling demotivational buttons, cards, t-shirts, and posters.
I wouldn't recommend a visit if you're already depressed.