1. If your idea is so good why is it take so long to succeed
2. Is it worth spending effort in to it (time and money wise)
3. Does it give you joy...
In design and creative industry, they call the idea "the baby". Something that they think it's so good and they will do anything to protect it. So it come to the time, they have to admit that their idea cannot goes on...and it hurt as it's to "kill the baby".
What about something that we are doing right now and it take to long to succeed.. May be its time to reconsider... Whether it worth continuing or you may have to except that you have been defeated and move on.
Only you, who know best.