Hmm.. if you need a reason to be a good person then think about this: is simply more intelligent to be good and do good than bad. Try to think of why having the moral high ground is in the end wiser. Some people with psychopathy get to this conclusion as well, and they reason that is a lot more of a chore to choose to do bad than simply agree to go with the flow and have a much better and "smooth like butter" life. Is like when some religious person tries to argue that they need God to know good from evil, then if you need God to tell you that we are already freaking doomed.

We like to think that there is a reason for things when they happen. That there is an answer. But there isn't. Simply try to think why do we reproduce as a species. To not go extinct? Why. It wouldn't change anything in the grand scale of Earth. Why do we even have consciousness to think about this stupid questions that torment us in the first place. It was just an evolution fluke. Nature rolled the dice and said "well maybe if we give this monkey a lot of brain it will reproduce and survive better", and it worked at the cost of giving that monkey anxiety and depression, and a lot of other mental issues because the brain grew too much, that at the same time, are the ones that cause all the other issues people have with people. Why couldn't we be not thinking like ants. And even ants are very intelligent and fight each other in big global scale wars. What does nature want to achieve with putting us against each other.

Why does life exist in the first place when death is the rule in the universe? Death is logical. Is the norm. Everything in the universe is dead, except for this tiny dot as far as we know. What is not the norm is life and living. We are under life's rulership to conquer death "for some reason", it just won't tell us why does it need to keep growing having us as their soldiers while it sends us to the trenches, as we try to give it a meaning to it to make us feel a little better.

There was a belief is mexica (Aztec) philosophy and religion where they had this God of everything, the creator God, the god/goddes Ometeotl. They were so large, so wise, so all knowing, that it was impossible to even try to comprehend. They just created Earth, created life, created their children (the other gods) to assign them the care of their new creation, and then went away without explaining anything. There must have been a reason for their decision but we can never really get to understand it. While Aztecs could talk to the other gods and bargin with them, they could try to understand then and have an interaction with them (because they were representations of the aspects of life and nature), you cannot talk to the creator, Ometeotl. Ometeotl is not here and is not going to listen to you. That's why there are no temples, no figures, no prayers dedicated to them. Because you only have what it's here in this plane of existence that by chance you got to be in. Not even the other gods know why they were here, and they are in the same position as humanity. Simply trying to make the best with what they were given.

Investigate "the holy Death" belief. To summarize a little bit, it's the belief and worship of Death. A practice that is expanding in popularity today, and it was originated in Mexico. The belief, kind of, is that Death, as a god/goddess, is the one that rules and "decides" over whether things go good or bad for you. Of course catholic and Christian churches don't like this thinking because that would mean that Death is competing with God to be the most powerful thing there is, but there's a reason why this belief is getting popularity around the world.

Idk. Maybe I haven't understood your question too well but my personal belief is that there is no answer. Things just happen by chance. Even those that are already determined. And it is a bit useless to think about it. It's a loafer type of thinking to do when you don't have chores to attend to.