If you want to know more about happiness from a scientific point of view, read or listen to experts like Daniel Kahneman. For example:
"My theory is that a founder’s happiness is tied to the rate of change of their startup’s success. In other words, your happiness graph is the first derivative of your success graph."
He is stating a theory, not a peer reviewed scientific journal. He isn't saying it is a fact, just a theory.
Personally I found his first derivative theory to be interesting and in many ways true of my life.
I know when things feel like they are about to go well, that is as enjoyable as when things are actually going well, but when they slow down I become unhappy.
If you have concrete evidence his theory is total garbage, by all means post it, but providing a random link and saying that anecdotal evidence is complete garbage is obnoxious.
Maybe someone who has the time to spend to prove the OP's theory or disproves it sees this post and it becomes a landmark paper you feel comfortable citing or reading.
It isn't the OP's job to prove it. His job is just to provide something interesting and insightful for people to read which helps get his startup's name out there. In my mind he accomplished both parts flawlessly.
Her* sentence fits the second definition of theory.