Exactly, you really don't seem to understand the point I'm making. I'm saying that if a child is born with a deadly genetical disease we should not be content with saying "oh well, that's how the world works, it's because that way someone will really appreciate having a healthy child, so it all makes sense FOR US, hence it's all good", as you said/implied.
Not to sound too dramatic, but for me, there was far too much suffering in the world to turn a blind eye away from evil and I realized that a very young age that a benevolent God would have stepped in to fix it, wouldn't you think?(queue the atheism that led into nihilism for a decade for me, until I became aware of the evidence for this sort of thing and had my own experiences to shake me out of it) So, I have always rejected that line of thinking that life is purely a school and preplanned, etc because it doesn't really make any sense.
To finish my 2 cents on God, I think what helped me the most understand more of what were dealing with is the book Mind Trek from Joe McMoneagle. He talks about how when he had his second NDE he did an "inspect" and discovered the "light" he was initially greeted by that was unconditionally loving, etc. was not God but the "totality of self." He concluded that the experience gave him a different perspective on what God is, and that God is beyond our comprehension. I think the best way of viewing God is to view it as an incomprehensible, amoral "everything" that encompasses all the good and all the evil, since after all a real God would be omnipotent and all knowledgeable.
In regards to the question of evil, I'm going to call upon my background for this one, which is heavily in psychology and some neuroscience (which I know everyone here loves). I specifically have studied evil for a while now in a psychological context, mostly on the understanding of psychopathy, and there is a lot of theories for it. Some say its all down to the parents, other say its genetic, and others say its childhood trauma. There is no real, concrete indication or marker for when an individual is going to be evil. Evil itself is entirely subjective and a sociological concept, its a time-oriented concept. Many things the early Christians did could be considered evil today, and yet back then they believed themselves to be virtuous.
So, I don't think "evil" is a good word for describing what motivates people to do heinous crimes that are abhorrent to us. We can't track evil because it's just an idea and its subjective, but what we can track are other factors. I think what it comes down are things such as a lack of empathy, sadism, selfishness, among other factors. This is where neuroscience can be good, we can take brain images of people who exhibit psychopathic behavior (evil behavior) and see what their brains look like in comparison to "normal" brains. What we find is that 99% of the time they're different and have abnormal growth. In fact, the research was so startling the journal Science refused to publish it because they feared what the research showed! However, this does not mean just because someone has a "bad brain" makes them bad people. There have been many people who have that type of abnormal growth and, while they do show a lack of empathy towards others, they do not commit heinous crimes, and are in most cases very, very successful individuals. (I'm paraphrasing a lot here, if requested I can make a more detailed analysis and go into what brain parts I'm talking about etc and the professors involved in this, just don't want to now as this post is getting long as it is).
So, it's not just a lack of empathy that makes people commit these horrific acts, but they're motivated by a selfish desire to fulfill a fantasy of theirs that could be sadistic in nature. Its just the lack of empathy that allows them to commit that crime since there is no "break" to stop them (that break being empathy). I will say there are cases in which this is not always true and there are no observable trends before someone commits a horrible crime, sometimes they're on drugs and they are hallucinating (could that be a spirit motivating them to do it? who knows?) and other times people simply snap and in a fit of blind rage they take things too far and someone dies. Ultimately, I think it is a consequence of living in a universe of free will.
Really, it's all shades of gray and I think the afterlife and other spiritual realms are no different. Reality truly seems to be what the individual makes of it and it is always going to be mysterious. Take things in stride and use your experiences as your strength, I certainly do. I went through a lot of suffering early on in life, as many people do, and I do not call myself a victim. It made me who I am today and it made me much stronger than I would be otherwise. In retrospect, it all makes sense to me now how things happened the way they did. Perhaps that's what people mean when they call life a school, not literally of course, but in a metaphorical sense of looking back at the lessons the experiences taught you and how you became stronger from what happened.
As far as why people are born at a disadvantage to others, I do not know. I don't find the "life plan" compelling, because a baby born with genetic defects does not only bring suffering onto themselves, but the parents as well. Pure speculation, but it may be random and could just be that particular individuals biology and how their physical body was developed from a purely physical standpoint. We are both spiritual and physical beings after all. I think the majority of people would agree with this and find topics like biology, psychology, etc more tolerable if they acknowledged the spiritual nature of humans as well (which is surely needed, these fields are on their last leg now without it). Looking at the world through either a purely physical or purely spiritual perspective lacks the scope necessary to accurately explain why things happen and to explain our reality, and in my opinion, both are equally as necessary as the other in order to explain it.
I should mention that my explanation is only scratching the surface of what the nature of "evil" is. To summarize, I think it comes down to free-will, individual agency, a lack of empathy, selfishness, sadism, perspective, and humans interacting with each other in the large majority of cases. I am aware there is some compelling evidence spirits or entities can influence people to do certain things, good or evil, (thinking DMT), but I'm hesitant to call those entities "evil" even if they exist. Morality might be best understood as a bell curve and where people fall into it grants them the title of good or evil, extremes being on both ends, and the middle being the gray area that we all know very well.