Earlier quoted context omitted.
Being happy isn't a selfish goal, in fact buddhism looks at this as a non-selfish goal. Buddhism totally advocates for happiness[1], it is only your perception that happiness is selfish that is in error. [1] http://thinkexist.com/quotation/i_believe_that_the_very_purp... "“I believe that the very purpose of our life is to seek happiness." -Dali Lama
The quest of being happy is a selfish quest. Selfishness is a good thing to me. Helping other (altruism) is also a good thing - since it serves your own selfishness (makes you more happy to see people happy - especially if you made them happy). The only limit is the damage it may cause them (ex: encouraging sloth) The only bad thing is sacrifice - sacrificing the others or even worse, yourself, is very rarely a good…
So while maybe it could be argued becoming happy is selfish, actually being happy is not selfish. But then again becoming anything is selfish, I think the point is what happens after the point of becoming that thing. There is a lot of this logic in buddhism, which is why more importance is usually given to your volition for doing something than what it actually is your doing (think karma).