Some philosophers try to make the case that all behaviour is egoistic. This standpoint is also known as universal egoism. The first problem with it is that it goes against our experience and intuitions; we see much philanthropic behaviour around us, and also commonly experience it as the motivation for our own actions. Their response to this is that we are fooling ourselves because - as they say - it is always possible to explain it away by pointing at immediate, deferred or imagined rewards.
But does this hold ? I would say no, as being able to explain something away in one direction does not exclude it being possible in other or any direction. And it is perfectly possible to explain many if not most actions in philanthropic terms too. Bona fide companies for example, do add value to society eventhough they seek a profit. And even most terrorists and tyrants such as Hitler did imagine improving the lot of the world with their actions and sacrifices. So at best we have tie here.
The second problem with universal egoism - and the reason why it often leads to heated debates - is that it is usually formulated in a way - "all behavior is egoistic" - that could be seen as wrong use of language. This because the usual meaning of egoism is defined as an opposite to other kinds of motivations, and not as a term suitable to describe mechanisms that are supposed to underlie all motivations. That is, there remains a difference between consciously misleading others under the pretence of philanthropy, and honest philanthropy. Thus even if universal egoism were 'true', we still would experience non-egoistic motivations at the psychological level.
And continuing from this, also the concept of self is ambiguous in universal egoism, especially as self-interest also includes imagined interests. That is a terrorist that hopes to receive a place in heaven for sacrificing his life is also considered to be egoistic, but his 'self' apparently extends beyond death, and thus beyond what we normally call one's self. This is important, because if we start accepting such 'extended selves' as 'egos' forming the center of egoism, then we can explain all forms of philanthropy with extended ego's spanning village communities, nations, ...or even the whole universe. So someone doing something for the good of man, is doing something ...well for the good of man.
And this - translating back to normal language - is the same as saying that true philanthropy does exist, and not all behaviour is egoistic.
If you want to discuss this more in-depth:
Logis Show - Behavior/Universal Egoism=Wybo_Wiersma_25 - LogiLogi.org - Thinking beyond paper, agility outliving chatter, quality in openness