Humans are selfish by nature. True or False?

I say its true, I know a lot of people who read this blog will rebutt it, saying I'm pessimitic about life yada yada... Yep, let me show you examples to verify this.

In work, a lot of people will definitely cover their ass 1st before reaching out to others. Who do otherwise? I don't think so. Will one actually help others out 1st before settling their own stuff? One may argue that I should know how to prioritize blah blah blah, but what if I know I have enough time to do my stuff and help others in their work? I believe that there will definitely be a little guy speaking to you softly.... "Mind my own business 1st before minding others, I can't take care of yourself then I wanna care for others? People won't appreciate my help I extend my hand to help them" Or worst still " They never care for me, why should I do that to them?

My point here is, how many people out there really exhibit the value of "Contribution before recognition", how many people will expect something out of the person he/she helped? How many people helped out because they themselves can get some benefit out of it? Win-Win situation? That's BULLSHIT, BigWin-SmallWin Situation that is.