MNO Group study - Just a hoax

YES, today I found out a dark secret of MNO group study! NEVER believe that they'll pay you the maximum amount of money. Today, there was this game. My room was told that my room was the donor and the other room (at the same time there were also people doing the study, just different group/room) was the acceptor. We were told that each of us had 20 bucks and we decide how much we want to give to the acceptor in the other room out of the 20 bucks. If the acceptor decides to accept the deal, each of us will get what I donated and what he accepted with regards to my deal. And so happen that I decided to give 5 bucks just to test the system. AND LUCKILY, i was chosen to randomly pick anyone from my group to be actually playing with real money. AND VERY LUCKILY, I RANDOMLY PICKED MYSELF! OMG, this was my lucky day. So everyone else in the room left and the coordinator told me to wait while he brought my deal over to check out with the 'acceptor'. And he came back telling me that the acceptor does not like my deal and both of us get nothing. Zzz, what kind of IDIOT would choose $0 when he could get $5. So i walked out. Very fortunately the last guy left from the other room came out as well. I engaged him and yes, i asked. I want to know if he's really an idiot man. Guess what, he told me he donated 10 bucks and he got 10 bucks! ZZZ, THERE WAS NO SUCH THING AS AN ACCPETOR! WE ALL GOT CHEATED! Just coz I wanted 15 bucks and I got nothing!? WHAT KIND OF FKED UP PROFESSOR IS DOING THIS SURVEY! So the maximum he'll give is 10 bucks? Pls, NUS sucks. Who's doing the acceptor decisions? The prof? Hey, if i'm picked just give me the 15 bucks k. OR U CAN TELL ME IN PERSON YOU DUN WAN TO GIVE IT TO ME.