On the topic of friends and haters

The other day, I came across a quote, which made me think. Actually, I think there is a lot of things to think about in the simple one-liner: “if your friends no longer serve your interests, ditch them, they have become haters".
One thing is: what kind of friends are these? Among true friends: sometimes I serve your interest, sometimes you serve mine, sometimes we are too absorbed with our own problems to serve any other interests than our own - but in general, over time, our mutual sum of interests are better served when we do it together as friends than they would have been, had we not been friends. That a friend for some time does not serve my interests does not automatically make her a hater - what has the risk of turning her into a hater is if I started seeing her as such. If the "friendship" is of a more superficial kind, there might of course be some truth in it - but seeing friends as a commodity that can be ditched (and perhaps even replaced with more superficial friendships) if they don't serve my interests will not end me up with really trusted friends that I can turn to anytime if the going gets tough. The interesting thing is: most of us have old friends that we might not be in touch with as frequently as we once were (and we might not actively serve each other's interest as much as we once did) - but if we really needed them, they would come to our rescue without asking a single question. That they do not continuously serve our interests does not make them lesser friends than before. Just as I am not a lesser friend even if I do not continuously serve their interests - I will be there for them without hesitation, when they really need me.
Another thing is: if friends really become haters (and I do not see this as happening just because for some time they do not serve my interests) - why does this happen? I think it is always relevant to find the underlying reason - as it might be something I have done that made this happen, and therefore, I should perhaps better my ways rather than ditch the people who cared for and trusted the better version who once was me. Otherwise, it might just turn more friends into haters and I will end up becoming a very lonesome person.
But sure - if friends really become haters for no apparent reason, the end of the friendship can be a very possible consequence.
And of course - the underlying question that I should have addressed up front, I see now: what does it mean "to serve my interests" - is it something that my friends actively do - or is it enough that they do not work against my interests? I personally think that the latter is quite sufficient, I can even understand it, if my friends work against my interests from time to time. Maybe this is a sign for me that my interests are not always optimal?
But the one-liner “if your friends no longer serve your interests, ditch them, they have become haters" I find dangerous. It might very well cause people to ditch what they should have cherished as long-term trusted friendships.
Translated from "Noget om venner og modstandere"