You Have To Remember It Was Mac That Saved the Place

I think it was more along the lines is he was upset that most of the work and time he had spent was a total waste and that he was getting kicked out.
But you have to remember it was Mac who saved the place. If it weren't for his own fascination with the sky and his phoning back and telling Happer the details about it, Happer would never have come to visit.
If another guy had done it they would have been cold and calculating and offered the original $60 million and be done with it. They might even have kicked Ben off the beach as a "homeless" man. We learn all kinds of lessons about ourselves from this movie. That's one of the lessons, that some people choose to live in nature as that is where we all once were. We also learn how insane our money driven society is.

Mac didn't just save the place he found himself which travel often inevitably does for everyone. We watch him transform from a Telex and Electronics man coming from Houston where people are rude to and cold shoulder him into finding his humanity again. He started off with digital watches and ended up wading barefoot in the tidal pools.