Ideas are usually the first step to making anything, with writing being a good example. When one wants to write something, one grabs an idea, develops an idea into an outline, uses the outline as the basis for their draft, and then either begins to experience some satisfaction with their work or thinks that the idea tricked them and grow to absolutely hate what they have produced.
The latter is more probable to happen to writers than the former.
So, what does a writer do when they learn that the thing they have just created is an abomination, a testament to their own incompetence and that they would rather swallow each of its pages twice over before ever letting it see the light of day? Generally, it’s either throwing it back into the pits of oblivion (via the command prompt’s delete function if one is feeling extra regretful) or scrapping and recycling it.
Recycling usually involves either the reconstruction of whatever idea that writer was working on into a new and fresh form, or an extrapolation of some of its aspects to use in a different piece of fiction, such as a series of events, a setting, or a character.
One could argue that recycling a manuscript one thinks is being discarded is somewhat inevitable to a degree, since even if the product which one has come to despise so much has been obliterated, the idea it sprouted from can remain in its original form. Regardless of what happens, some elements could always be reused in another manuscript, even if they’re only names or half-finished witty lines. Would it be really sensible to deliberately avoid using anything from that manuscript in future projects, however?
Some time might pass before one decides that one particular idea is hopeless, though. There may be multiple rewrites, lengthening, shortening, redesigns, reimaginations, until eventually something is considered satisfactory enough to leave alone or take to another level or deemed irredeemable and destroyed.
Personally, I believe it has something to do with the writer’s perspective and how it relates to the manuscript’s subject matter and/or essence. Someone who is about to begin work on a book of short stories that are exclusively sci-fi and fantasy might experience some frustration at having to work on finishing a troublesome and unsatisfactory piece of speculative fiction before they can do so, for example.
I guess what I’m trying to say with all this is that if you hate everything you write, then congratulations, because you’re a writer.