The concept of utils as a common denominator for peoples value judgements or well-being is a dead-end. Economists use utils but that's only for working with ordinal preferences in math.
I do think that ultimately, people are guided by consequences even when following strict principles. E.g. not negotiating with terrorists leads to better outcomes in the long run.
Time is an essential component in these deliberations.
Human action is decided by peoples' preferences. Preferences are a list of desired outcomes. They are ordinal. They are personal to each individual. Valuations can be thought of as moving up the list of desired outcomes. The most desired alternative has special names: goals and ends.
Since preferences are ordinal they can't be summed. This gives rise to the concept of marginal utility and opportunity cost.
Buying a pack of cigarettes is not irrational because preferences are subjective. Might regret it later though but that's simply you modifying your preferences.
I would argue though that if you modify your preferences frequently, you are indeed an irrational person. E.g. buying a pack of cigarettes and always regretting it later.