Let's say, hypothetically, that you wrote a novel.
And let's also say that hypothetical you is a slow writer and took about two years to write and edit the novel. Unfortunately, your hypothetical novel is an unreadable pile of garbage which you may or may not be able to fix, and even more unfortunately, you don't realise that until now.
Should you trunk the novel?
Welcome to the sunk cost dilemma. If you trunk the novel, you write off all your time and effort. If you keep working on it, hoping to somehow turn it around, you're pouring yet more resources into the project which may also have to be written off.
People are naturally loss-averse. That is, they value not making a loss of £100 more than they value gaining £100. This leads to the sunk cost fallacy, wherein people commit ever more resources to a failing project in the futile hope of saving their initial investment. (See also: Concorde.)
That's why my gut instinct tells me not to trunk the hypothetical novel: I think of all the hours of work, and I hate to write them off as a bad investment. Perhaps if I just put in more hours of work, I can rescue the project. But thanks to the sunk cost fallacy, I realise that that's irrational - just a stupid instinct interfering with logic.
The hypothetical investment is a writeoff. It's time to move on.
Winners never quit, and quitters never win, but those who never quit and never win are idiots.