Compassion motivates people to go out of their way to help the physical, mental, or emotional pains of another and themselves.[0]

I'm not sure how to approach such a sensitive and unknowable topic. As a human, I cannot hope to be above the influence of emotions like hope and fear. From this post I hope to gain some perspective. Emotional perspective is instinctual, intellectual perspective requires thought.

Compassion is an instinctual human trait, one need not be taught how to feel compassion. It is borne by fear and hope.[1] Fear that one might one day find themselves in a situation of need, hope that others might reciprocate that selflessness when the time comes.[2]

Compassion is unregulated, unlike other forms of action. One cannot feed "too many" of the homeless. One cannot provide support for "too many" of the infirm. One cannot save "too many" rainforests or plant "too many" life-sustaining trees.

...can they?

Is there a point at which the cost of overpopulation is greater than the cost of a life?[3]
Is there a point at which the cost of food scarcity is greater than the cost of oxygen scarcity?[3]
Is there a point at which the cost of inexperience is greater than the cost of poor quality of life?[3]

Is action, borne of fear, selfish by nature? Or do the ends justify the means?

[0] https://en.wikipedia.org/wiki/Compassion
[1] One could argue that compassion could exist without fear, though I'm not sure the concept of evolution would support that argument
[2] One could argue that they are simply virtuous by nature, though I would argue that is a result of insufficient honest self-reflection
[3] One could argue that these exact observations are false dichotomies, though I would urge you to engage with the concepts rather than the text itself. There is no meaningful distinction between consequences, the point is that every decision involves a tradeoff which, at global scale, has a potentially fatal magnitude.

P.S.
Please don't conflate a question asked without context with a call to action. There is no call to action in these words. If you see an answer to these questions, please do not argue for action. Address the question. Add your perspective. I present these questions without context and without perspective, there are no moral implications to the pursuit of knowledge as fact and reality would continue to exist even if humanity did not. Thanks for taking the time to read and consider.