Somebody paid for ALL votes that don't trace back to the original premine. You bought or earned HP and that HP powered votes. In this case, one person submits the HIVE and designates an account, and then they get their curation back as votes.
It's not complicated, but some antagonists are willfully refusing to acknowledge that it's still curation, just layered so everyone receives their curation reward as votes.
Saying HSBI is curation is dumb, it votes but doesn't curate. Curating include the action of reading the post and giving it an apropriate share of rewards.
You can do a random dbuzz post and get few $$ hsbi vote as long as you hold enough units, if that's not vote buying idk what it is, oh my bad it's not vote buying it's "layered curation".
That's the whole issue with HSBI, you get reward even for spam/ect