On the one hand, I know that my work has quality and I have the sort of skill necessary to publish (having done it three times now), but on the other hand, I recognize that having a professional editor work with my stuff improves it, sometimes *dramatically.* It's good as written--it's better as edited.
If I self-published, I might get some of my own fan base to read my stuff, but then I wouldn't have that crucial editing step to refine it and make sure it's exactly what I want it to be. And for a reader, new or old, to read something by me that isn't the best I can make it, it's going to be disappointing and in turn *hurt* my writing career.
I believe there's no such thing as bad writing, only *incomplete* writing, and if you skip the crucible process of editors/agents/rejection/submission/acce
Now I have to say, there are some people who skip the "gatekeepers" entirely and hit one out of the park with a self-published work. And more power to them--really! But writing a break-out novel is like hitting that history-making home run to win the Cubs the pennant. You *could* just step up to the plate and try your luck, or you could do a lot of batting practice with a lot of coaches (agents and/or editors) who beat you up so as to make you try harder.
Ultimately, I firmly believe that as frustrating and gut-wrenching as the process sometimes is, you *need* to go through it. You need to build up that perseverence and belief in yourself as a writer, and you also need to make sure that whatever you're putting out there, you are really ready to put it out there. Because if you jump the gun, the one you're ultimately hurting is you, not the editors/agents who pass on your stuff.