How do you counter the psychology of FF?

So Sunday I had three games where we ahead and up in gold. My team FF'ed successfully twice. One time two of us voted no and we won. Another game this morning. We were up 6k gold and 3 towers. A guy started an FF. Later another person asked if we should FF? we won easily. I asked in chat, twice and after the game. Why did you want to FF? No answer.

My best guess is someone felt behind or they weren't getting the kills they wanted or they didn't like the down time of being dead. They were not the superstar they envisioned themselves to be. But that aside, how does one counter that in a match? Are there any magic words that we can type in chat to keep morale high?

"We got this." "They make a lot of mistakes." "Their team isn't very good."

What works for you? This is really annoying. The reality is most players could defend, play safe and win a late game even if behind. Every time there is an objective taken and kill, I add "GJ" but this is not enough.

Another psychology is people would just rather play a winning game. But why do they decide they are not going to win? How do you get them out of the tunnel vision? The funny thing is come backs are some of the best feelings in gaming. I don't get why people don't try more.

Help appreciated.