What they do say is that after a certain point -- when most needs and some comforts are met -- adding money does not increase happiness.
Also, just in general, your life experience is not a substitute for data.
It's not a substitute for data when generalizing about other people. But data is no substitute for life experience when making decisions for oneself.
The guy said "I don't buy those studies". If he'd said, "Well, that may be true, but that's not how it worked for me". We're talking about money's relationship with happiness-- presumably we're not talking about just 1 guy.
And regardless, he didn't read very carefully. His personal data SUPPORTS THE STUDIES. To simplify it further: Flat broke = correlates with unhappiness (it's scary and you can get hungry). Once you are NOT flat broke (make enough cash, have enough cushion to not worry), money ceases to correlate with happiness.
There are actually quite a few studies out there that show no correlation between money and hapiness once you are "safe" (have a little padding and enough $ to eat, have decent shelter, feed your family, etc).