I don't think the OP is a disgruntled passenger who didn't get what he paid for but wanted.

BA were looking for volunteers to give up their seats on the OP's flight because it was overbooked. BA were going to rebook these volunteers onto flights the next day.

The OP offered to help BA out by giving up his seat on his original flight if he could be rebooked onto the earlier flight, which also had availability.

Despite this being a wonderful solution whereby the OP could have been rebooked on the earlier flight when there was no longer any chance of selling tickets for it, the reply was no.

Had the OP taken them up on their original offer, BA would have paid for a hotel and meals, and would have lost the opportunity of selling a seat on the next day's flight at a premium price.

If nobody volunteers to give up their seat on the OP's flight and fly the next day, BA are then on the hook for IDB compensation, as well as hotel and meal expenses.

How is any of that the OP being a disgruntled passenger who didn't get what he hadn't paid for but wanted?