Man gives a homeless guy $1, but the man's reaction to it is just too good

I had an encounter with a homeless man last year that I'll never forget. 

That day, my boss surprised me by taking me to lunch. This was wildly unexpected because we weren’t particularly close, but I was very appreciative of the gesture. It wasn't the lunch that stuck with me, but what happened immediately afterwards. 

He told me to meet him at a pretty fancy restaurant downtown that I had never been to. It was at a busy area of downtown.

“Do you have any change, Sir,” a homeless man said to me as I approached the front door of the restaurant.  I searched my pockets for coins, but I unfortunately had none, so I shook my head and walked past. 

My boss was waiting for me inside. He must have seen me talking to the homeless man because he quickly said: 

“That homeless guy is the dumbest man I’ve ever met! Every time I come here, he's standing outside. And every time I come here, I offer him the choice of having a $1 bill or a $5 bill. Every single time the stupid guy chooses a $1 bill... like he doesn’t know a $5 bill is worth more money!” 

He seemed pretty excited about showing me how stupid this homeless man was, which made me feel a bit awkward. So, we went outside, and he called the man over. He held out a single dollar bill and a five dollar bill and asked which he wanted. The homeless man cracked a small smile, chose the single dollar, said thank you, and walked away.

At this, my boss erupted in laughter. 
      
“See? What a moron! Every time I come here I always think he’s going to wise up and take the five bucks, and he never does! What a buffoon!”

My boss and I spoke a bit more and soon he left, and I stood in front of the restaurant, looking for the homeless man. I saw him sitting close by and walked over to him.

 “Why did you take the dollar? You do know a $5 bill is worth more money, right?” ''

He looked at me and cracked the same small smile as before.

“Of course it is. But if I take the 5 dollars, he'll stop giving me money.”