View it this way, money can't buy happiness, but can buy stability.
One of the main reasons of depresion are economic problems, so it takes part in the happiness part.
Just consider it this way, as long as you have money you can focus on the most important aspects of your live, family and friends, but if you don't have money then you need to make a living for yourself so you can be relaxed and enjoy the time with them.
It's a hard question, but it can be reduced to this, if I had to choose between tons of money and my friends, then I would choose my friends =]
"Give each thing the importance it needs, never give anything more importance than it needs or less that it deserves"