He shouldn’t have promised something that he couldn’t afford.

If you tell a friend that you only see once a year, «I promise, we’re going to go to Japan on vacation someday,» that friend has good reason to take that promise with a grain of salt. It’s very easy to make empty promises when both parties know that the plans you’re talking about probably won’t happen.

It’s a totally different situation to promise your kid something you don’t plan to follow through on. Kids always listen to their parents, and they will almost certainly remember something their dad promised them five years ago. Of course, there are different levels to this. Some kids don’t hold onto every word their parent says, and they might not remember all the promises they make and don’t keep. But if a parent makes a very specific promise with conditions (if you do this, I promise I’ll do this), it’s not cool for them to renege on that promise if the conditions are met. It doesn’t matter if they made a promise to a kid. Heck, it’s probably worse to make a conditional promise to a kid and renege once the conditions are met, and then some.