(I wrote this before the FTX scandal, so it was not intended as part of the following discourse.)
I don't think it makes sense to replace the word "altruism" in the name of the "effective altruism" movement, but I can think of a couple of reframings of "what it is people who call themselves 'altruists' tend to be and be pursuing" which might be interesting or even useful to think about. These reframings can be discussed through the thought experiment of "what other words could be used besides 'altruism'?".
Omnism
"Altruism" could be seen as "an ethical orientation toward beings other than yourself". (Caring about other beings, acting for the sake of other beings, etc.) If we want an alternative to "altruism" but still want our ethical orientation to end up including beings other than ourselves, we can use the term "omnism", for "an ethical orientation toward all, or the whole of, morally significant beings". ("Omnism" from "omni", meaning "all".)
One potentially useful difference between "omnism" and "altruism" is that if you care about all morally significant beings, you care about yourself, because you are a morally significant being. This is something an "other-oriented" altruist might miss.
Another potentially useful difference is that omnists might remember more often to think not of specific small-scale interventions with certain "others", but also of collectives, systems, or the overall collective or system (the whole). I can see why a small-scale mindset is practically useful, but it could be good to bias yourself against that to some extent.
If I adopt the identity of omnism instead of altruism, I feel balanced and interrelated, plus some hard-to-express feeling from how the word "holism" or "holistic" is loaded in our culture or in my personal cultural experience.
Aletheism
Altruism and omnism are both about an orientation toward well-being, and potentially "engineering reality" to produce well-being. (Maybe that could be called "welfarism"? (Maybe not the best term).)
"Aletheism", by contrast, could be seen as "an ethical orientation toward the truth, knowing it and speaking it". ("Aletheism" from "aletheia", meaning "truth"[1].) But, this can include the goals of altruism/omnism if we understand that to really understand moral truths, we must act. For instance, if you really understand that something should not be, you must act against it if you can. That which should not be inherently calls out to be changed into that which should be.
One potentially useful difference between "aletheism" and what I guess could be called "welfarism" is that aletheists are biased against manipulation, misrepresentation, self-delusion and premature epistemic optimization.
When I try on the "aletheist" identity instead of the "altruist", I feel a clarity, honesty, and lack of controllingness, as well as perhaps some hard-to-express feeling from how the word "truth" is loaded in our culture, or in my personal cultural experience. As an aletheist, I follow reality without an agenda, and because moral truth is part of reality, I try to do the right thing. (That may make aletheism sound like a clear winner over "welfarism", but maybe "welfarism" is more "muscular", competitive, and effective, at least in the short-term. My preference/bias is with aletheism, for what it's worth.)
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I chose this term not with ancient Greek or Heideggerian resonances in mind, but because it's the modern Greek for "truth" according to https://translate.google.com/?sl=en&tl=el&text=truth&op=translate