To make everyone happy one must control everyone and everything. Which means end of free will. What’s the fun in that. Actually that’s nothing worth making.
Now if there is free will there is karma. Souls are numerous but limited. Which means rebirth.
Which also means previous life karma being forwarded to next one.
That also means some people even if being good in this life suffer due to previous lives.. and being bad enjoy due to previous karma..
There is a way to end all suffering that’s being free from the cycle of life and death. And the way to get that is being like God. Also God don’t only care about humans. If a human make an animal suffer he will also get the return package.
May be God was lonely and wanted to create something for fun. But surely he didn’t make people suffer for no reason. Free will makes us vulnerable to various sins which make us suffer.
Justice is what he does..
He never makes anyone suffer for no reason but can pardon a person who genuinely regrets and wants to improve.
The one who becomes like THE ONE gets free from this cycle
So the answer is God don’t make everyone happy because he is all powerful and thus gives justice.