You know one more thing about Spinel that makes it all sadder?
She had no plan. Not a coherent one, anyway.
It all boiled down to "Find the biggest, nastiest, most dangerous things I can get my hands on, go to Earth, and GET all those stupid jerks for what Pink did to me!"
That was it. And she had no plans for after the fact.
Even if she had won, I have no doubt that she would not have found satisfaction in victory. It would have been seconds before she was breaking down and begging for forgiveness from atop a pile of corpses and shards, regretting everything she'd done.