A time horizon is simply the length of time an investor plans to hold an investment before selling it.
But for more of a practical application:
The longer we wait for a return on an investment, the more patience is required.
However…
When deciding when to quit, we often don’t consider an opportunity to do something else.
It’s never easy to decide whether to quit. There is no telling how things could turn out if we had the guts to stick it out a bit longer.
But I have learned over the years that people really underestimate the power of opportunity costs (the resources that could be spent on something else) and sunk costs (what’s gone is gone, and it isn’t coming back, so cut your losses now).