I believe this one is very closely tied to the "...Cant by me love" one, and this is how i see it:
It comes down to the money can't BUY you happiness/love, but it can afford you alot more OPPORTUNITIES to experience or find that happiness/love. It's a security thing. As long as i have enough to get bills paid and still have a liiiitle fun, im happy, and thats wat counts, but If you are eeking it week to week (and i mean REALLY eeking it!) then you won't have the opportunities to get out, socialise and enjoy yourself...you can only ever have soooo many quiet nights at home before you go stir-crazy and NEED to get out. Trust me, i work nightshifts, and you dont realise just how much you depend on social interaction until you do this.
Like Audi said, it's a freedom thing...the freedom to no have to worry if you have enough to go to that rave, or can afford to go on that track day. End of the day, stress/worry is the anti-christ of happiness