By immediately calling out such an unreasonable and astonishing price, he thought that it would make him look more powerful. However, he didn't know that he had already committed the big taboo of auction. All of these people were people of status in the Breezy Plains. Which one was easily frightened? To show such urgency over this item only told other people how badly he wanted it. At the very most, it could make some bidders who had close relationship with him give up bidding.
However, he didn't have to raise the price so high if he had wanted to dissuade close friends from bidding; just adding to the base price by a little would achieve the same effect. If it was something not so important, close friends would certainly give him some face by not bidding for it. If it was something very necessary, then 5,000,000 wouldn't be able to scare those rich families off.