How to know it's "Time to Call it Quits" (I will not promote)

I spend a lot of time talking to Founders about whether or not they should "fold the tents" with their startup. It happens - a lot. I've been through it personally multiple times, and yeah, it totally sucks, but I think one thing I've learned in that time based on my own experiences and talking to lots of other Founders is that there's an interesting decision process to follow: 1. ***"I'm keeping this going because I just need more time to be successful."*** If there's clearly light at the end of the tunnel, and this is what you want to be doing no matter what - then yes, it **may** be worth it to keep going. 2. ***"I'm keeping this going because I don't want to fail."*** This is actually the trap that most Founders are in. They are long past the point where they believe the startup will be successful, **they just don't want it to fail.** I've never met a startup Founder who succeeded by simply avoiding failure. I got into this doom loop myself multiple times where I was so preoccupied with "saving" my startup that I lost sight of the fact that there wasn't any opportunity worth saving. No one wants to "save" your dying startup with an investment. At some point the only person that even thinks it's worth considering is the Founder, who is often in a very isolated place at the time. **Curious for folks here who are either on the fence now, or have been on the fence before, what decision criteria you used to press on or "fold the tents".**