You see bots don't make money off of curation that is what they give back to their delegators, their profit comes from the vote buyer buying the vote, and they can give a 30 SBD over the 50% to the delegator and still keep 50 SBD for themselves just by having a bot less profit but still profit with no risk, even lowering the buying price from 200 to 80.
And you have to be realistic man, the bid bots are owned and delegated to by the people pushing for HF21 you think they are going to screw themselves?