Philosophers from Socrates onwards have never tired of asking why anyone should be moral. A more interesting question is why anyone should be prudent. Why should I care what becomes of me in future?
Philosophers have always had a weakness for prudence. From Socrates onwards they have laboured to show that the truly prudent person will always act morally. They would have been better employed questioning self-interest.
Why should my future goals matter more than those I have now? It is not just that they are remote – even hypothetical. They may be less worth striving for: ‘Why should a youth suppress his budding passions in favour of the sordid interests of his own withered old age? Why is that problematical old man who may bear his name fifty years hence nearer to him now than any other imaginary creature?’
We need not share George Santayana’s view of old age to see that his question is unanswerable. Caring about your self as it will be in the future is no more reasonable than caring about the self you are now. Less so, if your future self is less worth caring about.