Hm. It seems like a couple of your examples may involve value drift due to behavioral reinforcement. The behavior of buying expensive stuff gets reinforced when friends act impressed, or the behavior of being a jerk gets reinforced when it gets you laid. If it's entirely behavioral phenomenon, it seems possible that the "value drift" is only a drift in revealed preferences, not reflective ones.

Schelling fences or similar come to mind as a way to prevent this sort of behavior change in oneself ("be a decent person always", "donate 30% of my income").

I've had a fair amount of success detailing policies like these for myself to follow. Typically my policies have associated lag times before policy changes take effect, which I've found to be key for experimenting to see what's convenient, workable, and makes reasonable compromises while not ditching the entire policy whenever I encounter problems. I don't think the effectiveness of these policies is best explained in terms game theory, however. The way it feels from the inside is, if I draw up a policy when I'm in a relatively high-willpower state, it's as though I can "lock in" a bunch of future decisions related to the policy that I'll later make using minimal willpower.

If people are interested in the details of what I've learned makes for effective policy administration, I could probably write a discussion post about it.