If we can’t walk away from costs that have gotten out of hand, we commit the old “throwing good money after bad” mistake.
It’s not just money that gets sunk. Time, effort, personal pride, etc… can all get poured into a passion project and we let it get too personal and never let go when it’s time to let it go.
Let sunk costs be sunk costs. You can’t raise the Titanic, but you can drown yourself trying to dive down and lift it back up from the deep.