Money can't buy happiness.

Money does not buy happiness. What money does buy is comfort. You can live in a nicer house, drive a nicer car, play more video games, and eat at nicer restaurants. However, comfort =/= happiness. I do not believe that one can fill the void in one's life with material things. Material things will not give you a sense of purpose or belonging. Material things will not share your company, laugh with you, or cry with you. Material things will not love you back.

I think there is an almost an exact quote like the bolded part in an episode of the Simpsons.

Anyway, I think you have a good point here, but I disagree that comfort =/= happiness. Being comfortable is bliss for me, particularly when I sleep in my bed, which is something that I take for granted but isn't guaranteed at all, so there is an indirect link there. I may not feel happy when I got a new pillow or something, but I am happy when I go to bed. And say you have a beloved cat or something, and you're very happy with it, but then you have no money and can't feed it, leading to its death. Another indirect link.

And, I think you must first identify what the phrase was referring to. If it meant that temporary feeling of happiness, money can indeed buy you happiness, be it letting you buy that thing you wanted for a long time, or whatever. However, I doubt that the phrase was referring to that. I believe it is instead referring to persons that doesn't understand the limits of money and power and try to get whatever they want with them, like friendship or love that would bring you happiness if you had obtained it the right way, but not if you try to buy them.

Concluding, I think the phrase should not be taken literally and that it means something more along the lines of "knowing the limits of [money, power, and material things], specifically in the realm of emotions and relationships."