Do people really think that this is a case of Tall Poppy Syndrome?
What, Roko needed to cut down a successful Spookybot to ease her own bruised ego?
There's a few problems with that line of thought. Namely, Spooky isn't "successful", they're a secret AI that operates in the background, whose existence is the kind that's just whispered in certain circles. They aren't a businessperson who spent years building a financial empire and decided in later life to do some good with their money and donate it to worthy causes. Spookybot literally said they'd employ blackmail or industrial espionage. Think about that for a moment. Where did Spooky get their money from and disconnected are they that they can drop two billion like it was nothing. Given how Spookybot technically doesn't exist, than there has to be something along the lines that isn't legal, be it skimming pennies off an account here and there, or claiming dead accounts for their own use. We don't know, but given that Spooky only did it anonymously kind of says they don't want anyone investigating them. Which screams shady.
But let's put it another way - swap out Roko and Spooky with Hanners and her mother. Beatrice is one of the most powerful people in the world and they suddenly donates two billion dollars after Hanners said she's doing some charity work. Is that Beatrice being a decent person, or is she trying to buy Hanners' affection? Likewise, is Spookybot trying to be a decent god-like AI, or are they trying to buy Roko's friendship? Given their previous interactions, I'd say it was the latter.