I agree with most of what you say with the exception of the above. GGG opened in the market at a very, very short price before a single penny was laid on him. Bets wagered did not dictate his odds. Likely bets, dictated his opening odds and likelihood of him winning dictated his opening odds There has to be an opening market and that market is almost unbackable. Thats the bookies nobody else. I don't think bookies are evil not at all.
Yeah this is why you try to find a main line bet it's just who wins or loses but it might be hard to get that.
https://www.givemesport.com/1480346-one-punter-bet-100000-on-anthony-joshua-to-beat-andy-ruiz-jr Errr yeah, those sorts of bets don't always work out either, some nutcase had £100,000 on Joshua to beat Ruiz, if AJ won he would have only made £5000 profit. I hope the man is OK LOL