The Sunk Cost Fallacy is a [email protected]#$.
It's a cost that you sustained in the past (be it time, money, energy, whatever) and cannot be reversed, cancelled or undone.
The fallacy is that yet knowing about the sunk cost of a project, you are often tempted to justify your future investments because of your past (most likely lost) investments.
The sunk cost should not influence your future decisions, yet it does. And the outcomes are often delusion, sadness and stress.
Cut your losses
You might get emotionally attached to your projects.
Your idea "is awesome!", yet your expectations are not met by others.
You can't possibly understand why your project doesn't do as well as you have hoped.
You spent the last month contacting potential clients, shipped v1/v2/v3/Beta1 and Beta2, optimized your landing page to maximize conversions.
Yet nobody gives a flying fuck about your project, although your research and feedback received.
This is when you should cut your losses.
It's perfectly normal to feel stressed/disappointed when you need to cut your losses and move on.
But you need to realize it.
If you don't realize it, or realize it too late, you get burned.
You get burned by your own emotional decisions, which should have been rational all along.
It's business decision making after all.
It's not kindergarten where you just cry out loud and a nanny comes to cheer you up and console you.
Just move on.
It seemed a good idea in theory, but people have better things to do than to feel pity over your failure.
And you do too.
Learn from your mistakes
You have nothing left to do than to learn from what you did wrong.
Write it down.
Visualize the process you followed.
Maybe it wasn't that good after all.
Did you first of all understood that there was a real value for your potential customers, or you just thought people would donate you money because you spent months on your pretty project?
As you might have noticed, You is mentioned quite a few times in this post.
This should make you reflect.
It's not about you, but about market, niches, interests, potential clients, value proposition, communication, marketing, connections, content.