So if someone had 10 steem at hand, they probably just have 3-5 in hand after using bidbot.
Not always the case. There are some services out there that some bid bot users among many other types of individuals use that allow them to set beneficiaries of the post to the service. In return when the post pays out they charge a small fee and send the payout as if it where liquid to the author. The service than down power it themselves. If someone is turning a profit that 10 soon turns into more and it snowballs till they get flagged or cash it out.
Well, they'd still have to take out 50% curation rewards now. And bidbots are not always profitable unless steem prices increase that week. I have in past many times used bid bots to trend my post but it almost never made any profits. But then my intention was never to make profits but to get more eyeballs to the content which I created with hard work. Of course, not all people use bidbots for that purpose.