People are asking "why would or how could the shooter do.." because dude is a sociopath. Does dude's actions seem like thats something normal people do to you? They don't and thats because sociopaths don't reason through the world like normal people, or they do, but they've been pushed to the point where they don't give af anymore.
The truth is you can't only blame the person, its the person's environment thats responsible for training them.
Every interaction you have shapes your world and your "code", remember that. That is true for all people, no matter where you grew up or where you're at. Some people are born fortunate enough to never have to have lived through or interacted with an environment that these cats grew up in.
As much as people may be pissed at the dude, and you have full right to be, you should also acknowledge that plenty of people failed that guy. Dude didn't have the same type of people or interactions around him like Nipsey or any other strong person may have had. Even if they're from the same area, hang with the same folks, they both had very different interactions. Big homies may completely have treated dude like crap rather than guide dude like they may have other cats. Nobody's experiences are the exact same and nothing is a one size fits all circumstance.
Only thing that will put an end to all of this is a lot of fukking empathy.