Yes I noticed the -10% ROI !! You are one of the forward thinkers protecting the innocent, fools and the greedy from them own weakness.
Maybe you could start a BIDDER RATING system for bot owners to use when accepting bids.
Bids would not be accepted from people with a low rating which they would get if they overvote late, or make bids 3x larger than the majority of bids already in place in a round. Malicious distruptive players trying to wreck bots reputation, or the greedy will quickly get a low rating and be rejected
To give you (another) example of stupid bidding - just this minute I check on a bot - 2 bids of 0.1 with a roi of 350%. A few moments later somebody has bid 1.0 and for sure by the time bidding closes there will be an negative roi because a few more bids of 0.1 or 0.2 will fill the bid.