Well, you're implying that I think selfishness is purely negative. I don't: I'm selfish in many other ways; pure selflessness can be just as bad (as you've very well described -- parents snubbing children because of a different sexual orientation!). To put in other terms, selflessness and adherence to principle are virtues in the same that bravery is a virtue; yet we don't aplaud the bravery (or selfless, or adherence to principle, etc...) of a suicide bomber much for the same reason -- the immense suffering the rest of their action caused to others. We would, however, aplaud this in (to use a hypothetical example) a fighter pilot defending his country from a nuclear strike by ramming the incoming bomber with his aircraft after they've ran out of missiles or cannon shells.

I'll also point out that my native language is Russian, where there isn't a word like selfishness: there's egoism and egotism, but not really a world like "selfish". If you lookup "selfish" in the dictionary, you'll find a more value-free translation of the word.

My poor chances of physical survival would also not be due to compromising my values: it would be due to inability to adopt to surrounding society's values. Military service in former USSR, for example, is very different from Singapore -- bullying of nerdy/weaker/etc... enlisted men by officers is an endemic problem and has driven many recruits to suicide (lookup "Dedovschina"). The smart way some people took is by committing themselves to officer corps (for a much longer term) and (to fit in) becoming bullies themselves -- something I'd never be able to do.