EAs premise includes basically "all human lives are equal. Saving one stranger's life is just as valuable as saving your father's life (more valuable actually if the stranger has more years left than your dad), so you should donate your kidney to a stranger, not your father"
"All human lives are equal" then expands to "and there are more unborn lives than there are currently living lives, so it's more important to save unborn kids in 200 years by diverting AI catastrophe now".
I personally don't think unborn lives are worth anything, and as such I don't follow that jump. I don't feel a need to justify it either.
I think there's two additional easy ways to veer off the EA course.
The first is "how do we know EA is right about the charities?" The answer you'll get is basically "Sure, you can donate a kidney to your father and know it saved his life, you can verify that... but the people verifying your EA kidney donation does more good are smarter than you. They're rationalists. They do math. They know selling your kidney, which would have only saved one life, to a black market and getting enough money for 50 mosquito nets, which will save 20 lives, is the right deal. The spreadsheet says so."
I do not buy that the people running and choosing EA charities are actually the smartest people, especially when it comes to having a positive impact on lives. Sure, they talk a big talk, but I know for a fact that when I give money to a local shelter, the money gets used for good. I know for a fact that when I donated to a certain EA charity I won't name, the money went into "AI research" which is to say into the pockets of a rich white dude. I know for a fact that the average EA rationalist I have met does not come off as a caring human.
A second way that one can veer off the EA course is by deciding that one values some lives more than others. For example, if I live in a small city, I may decide I value the lives of orphans in this city more than the lives of the orphans in some third-world country. Sure, feeding an orphan in africa is cheaper so EA would say do that, but I may decide that the intangible value of improving my local community is worth more than "getting the most bang for my buck". I think this is also a totally reasonable argument, and in fact I would much rather live in a world where everyone tried to improve their local community than one where everyone used a spreadsheet to try and maximize their "best improvement per dollar".