You're right that pure strategy dictates you should only and always 1-up somebody if you're the 4th bidder, cause if you're wrong and everyone went over you'll get another chance to bid again.
But there's way more than pure strategy at play here. Maybe I'm sharing the row with a sweet old grandmother, and I can't bring myself to 1-up her on national TV when I'm gonna have to justify to all my real-life friends why I saw fit to throw Ethel under the bus.
On the flip side, if I'm in a position where I can confidently bid $1, I'm framing that photo and putting it on my wall. 50 years from now I'm gonna be telling my grandkids about the time I bid $1 on The Price is Right. It's the ultimate flex. After all, it's not MY fault everyone else went over.
Maybe you have a good reason for not wanting to go into extra bidding rounds. Maybe you don't want to give the other three contestants a chance to get their bearings straight and think things over one more time.
Or suppose it's 2005. The show's done live-to-tape. It's the 6th game. They haven't played a car game yet. If you 1-up, you know Bob will get annoyed and hurry you all into bidding again very quickly, and the winner will get 45 seconds less to play for a car.