Or okay you know what else I think of sometimes, with the whole “If Harry had had a good home life” and why Dumbledore needed him to not have a loving home in order to craft him into a weapon/martyr, is this: Dumbledore not even trying to stick his neck out for Sirius and not even questioning for a second him betraying James suddenly makes a lot more sense.
Because think about it: Dumbledore knows Sirius, he taught him for seven years and knew him afterwards in the Order. He’s seen the love Sirius had for James, saw Sirius leave his own family and basically become a part of the Potter family and yet, to our knowledge, he doesn’t even raise a hand to help Sirius when he’s arrested, just allows him to get sent to Azkaban without a trial. Whereas Snape, SNAPE, who is a KNOWN Death Eater (and we can assume he’s done some terrible things to become a Death Eater, especially one in the Inner Circle), Snape not only gets trial but gets off with no jail time based on Dumbledore’s word alone.
Why?! Dumbledore sticking his neck out for Snape but not for Sirius doesn’t make sense unless you look at what Dumbledore needed. Dumbledore needed Snape as a spy, and really, his plans were far better suited if Sirius was locked up, guilty or not. Because you can bet that Sirius would never have taken Dumbledore’s ‘Harry needs to stay with the Dursley’s" nonsense, he would’ve fought tooth and nail to get rightful custody of Harry, and then what? Harry would’ve grown up in a loving environment, Harry would’ve had someone to fight for him–someone with REAL knowledge of the wizarding world and (presumably since he was raised as a Black) some type of political savvy, even. Think of that! Think of the fuss Sirius would’ve raised during the Chamber of Secrets debacle. Think of what Sirius would’ve done to Rita Skeeter for printing lies about his godson if he weren’t a wanted felon. And we all know that Sirius would’ve been loyal to Harry over Dumbledore, and that was a problem.
tl;dr: Dumbledore is a sketchy mofo and I hold him partially accountable for Sirius Black’s suffering, and like 95% accountable for Harry’s.
The most important things are the hardest to say because words diminish them.