From some other fresh Related article:

The market's been driving money away from voters, but not the market for votes. Instead it's the market for delegation, as the bot owners have been in a full-force price war giving higher and higher returns to keep their delegators...
the vote-buying market is consolidating into a small group of very-high-volume users... it's getting less and less user-friendly to buy a vote and actually get anything out of it...
We may actually be on the verge of seeing bots being used for promotion only...

I advice reading the conversation below that post too.