There's a point when it's not fun anymore.
There's a point when it's not working, when people aren't excited, and when it's run its course.
There's a point where you regret it, when you can't move forward, or when you just don't care.
That's when you stop.
It would have been better to stop just shy of that point, but now that you've arrived, it's best to name it and put an end to it all.
Close the business, stop tweeting, reverse direction, change course, try again, or quit.
Knowing when to stop is just as important as knowing when to start.
Because most of the time, when you stop what's not working, you'll finally have the time and energy to go start what will.