I don't think very many people actually act in a way that suggests consistent optimization around a single factor; they optimize for multiple conflicting factors. I'd agree that you can evaluate the eventual compromise point, and I suppose you could say they optimize for that complex compromise. For me, it happens to be easier to model it as conflicting desires and a conflict resolution function layered on top, but I think we both agree on the actual result, which is that people aren't optimizing for a single clear goal like "happiness" or "lifetime income".

predict the person

Prediction seems to run in to the issue that utility evaluations change over time. I used to place a high utility value on sweets, now I do not. I used to live in a location where going out to an event had a much higher cost, and thus was less often the ideal action. So on.

It strikes me as being rather like weather: You can predict general patterns, and even manage a decent 5-day forecast, but you're going to have a lot of trouble making specific long-term predictions.