Time sucks and money pits
There's a fine line between a project that's turning a profit and one that isn't.
And discerning that difference--coming to terms with the fact that your hard work might not be paying off--is incredibly hard to do.
It's hard because it feels like your failing.
Hard because you have to ignore the sunk costs of the endeavor. To acknowledge that what you're putting in isn't worth what you're getting out.
And hard, because those resources--your time, your money, your effort--they were yours. You felt it. You lost it.
But acknowledging that it's not working when it isn't is the most sure-fire way to avoid the trap of investing more of your time, life, or resources into things that have no hope of working out.