The money’s already spent. Staying to “get your money’s worth” just spends your time too.

Money already gone cannot be recovered by suffering further. Staying in a bad film, a bad course or a bad arrangement to justify what you spent converts a financial loss into a loss of time, which is the scarcer of the two. The spending is a fact, while the next hour is still a choice.

When you catch yourself continuing because of what it cost, ask what you would do if it had been free. That answer is usually the right one. Leaving early does not waste the money, since the money went either way.