system
Given the following post, respond as if you're commenting on Reddit:
human
What was the point of Snape killing Dumbledore?

So, dumbledore's plan was to have Snape kill him, since he was dying anyway, cementing Snape's position with Voldemort and making him a more effective spy.

But a spy isn't much good if they don't have anyone to report to. And since dumbledore didn't let anyone else in on this plan, no one on the 'light' side knew of Snape's true allegiance. What did Snape actually achieve after Dumbledore died, besides trying to soften the effect on Hogwarts?
gpt
There were three points to it. One was to secure Snape's position with Voldemort so he could continue to help the "good guys" from within. The other was the Dumbledore was in quite a bit of pain from trying to destroy one of the horcruxes and would have eventually died from that curse anyway. Snape was ending his suffering. This also had the benefit of preventing Draco's soul being damaged from murdering Dumbledore. 

The final, and most important was to make sure the Elder Wand lost all its power. Dumbledore believed that if Snape killed him and he was ready and willing do die, it would not count as a magical defeat to the wand, and thus transfer ownership to Snape or anyone else. Dumbledore hoped that if he let himself die, the wand's immense power would just fade away. Unfortunately, Draco had disarmed him just before, so the ownership transferred to him unknowningly.