The point I was going for, was that the $25,000 win is several seconds old by the time the envelope is revealed. (And believe me, several seconds is an eternity under those conditions.) You know you have at least $25,000 the instant you figure out the puzzle - now, what you're hoping for is a large number to add to it. If you don't get any more, I can imagine the feeling being similar to, that of missing the bonus round but still having, say, $36,000 from the game.
I know that in my case, I was extremely happy when I knew the solution, and immediately after I gave it (knowing I've just picked up $25,000, but will it be more?). After a couple seconds, my attention at once turned to that envelope. And yeah, if it had been $25,000 in there, I was just going to make a conscious effort to continue the happiness from solving the puzzle. As Pat opened the envelope to look for himself, I saw four trailing zeroes and a hook at the bottom of the first digit. I was prepared to ramp my happiness a bit for a $30,000 win. When I finally saw the $50,000, there was a major shot of glee.
So, yeah, I can kinda see the mindset that would cause that kind of reaction, but there's definitely no excuse for letting that show on the air.