For instance, I do not like paying taxes and paying for gov't programs that I don't approve of, but I would take $200 and loan it to some small business in a developing country, it's called microfinance.
Do you not do this because you expect to gain more in return than you lost? In other words, do you believe that it will hurt you in the long run or benefit you?
Allow me to give you my own interpretation of this:
- you expect to gain a short and possibly long term good feeling - increase your happiness
- you know there is an overwhelming chance you will get the $200 back (people seldom default on loans in microfinance)
- you value the immediate use of the $200 (interest, spending, loan to different people...) less than the aforementioned good feeling, even factoring in the risks to not get the money back in its entirety
This is a selfish act which incidentally benefits others. Everybody wins. Selfishness is something we can hardly escape as human beings.
Note: what people expect and what actually results are not necessarily the same thing. This often leads people to conclude that an act was not selfish as the person who undertook it is now clearly in pain or unhappy as a specific result of this action, with no other gains to be found. This is either because things did not turn out to be as excepted or because the gain is elsewhere, unseen by the observer.
For this to qualify as rational self interest though (which is what clever humans should seek for themselves), the long term benefits have to outweigh the long term losses. If only as an expectation. Hence the need for a conscious and reasoned action.
This principle necessarily leads one to renounce instant gain resulting from the initiation of force or fraud to live a peaceful life within society. This is because one understands that his self interest is maximized within such a society, and can only expect to not be initiated force or fraud against if he does not do so as well, and he therefore wishes to live in a society generally structured around this principle.
This is the essence of libertarianism, whether people realize it or not. Those who do are rationally self interested, and rightly so.