Ahh, the age-old philosophical question of whether or not money can fulfill a person's life. Of course it cannot, I mean, the only thing that can fulfill your life is love and God and doing good in the world.
That person must have never been broke.
I've done some hard hitting research through mental health in relation to socioeconomic welfare to try to analyze whether money can actually buy happiness. Of course, the knee-jerk reaction is no, it cannot, but why is it that people with lower levels of income are seemingly less happy (on the whole) than people who aren't struggling for their rent, or their next meal.
So the first thing that comes into play when discussing happiness is Maslow's Hierarchy of Needs. We have probably all been made familiar with this chart through either psychology or health classes. At the bottom of the pyramid, there are things you need to survive, such as shelter, food and water. As you climb the pyramid, you require more and more to become truly self-actualized (the realization or fulfillment of one's talents and potentialities, especially considered as a drive or need that is present in everyone).
Things like love, sense of self, and pride are higher on the pyramid, because in nature we need to take care of surviving before we can love, and love before we can be self actualized (I'm paraphrasing this concept by a lot, but I think we all at least somewhat understand).
If a person cannot afford to pay rent, or feed themselves or their children, they use a lot of energy on those things, versus people who don't have to worry about it, and instead focus on being happy, or self-aware. For this reason, money can in fact buy happiness.
There is also a legitimate health risk to having less money. We all know the salad at McDonald's is about $5 whereas a burger is $1.12, and that's a big contributing factor as to why people who have less money are in worse shape (typically). Healthy food costs more money, and if your options are either not eating or eating a greasy burger, I think it's obvious what the choice is. The worse you eat, the worse you feel, and the less happy you are.
Aside from the cost of food, you also have to analyze things like money to own a gym membership, or time to use a gym. The more hours someone needs to work to make ends meet, the less time they have to focus on working out and recharging themselves mentally, which in turn can make someone's emotional tension build up quite a bit. Prescriptions and mental health treatment is also something low income people often go without. Healthcare is expensive without insurance, and without insurance, "extra" things like therapy and doctors visits are the first to go.
Stress can wear on a person's happiness to the point of developing problems such as depression, anxiety, or even eating disorders. "Happiness" may be hard to define, especially universally, but basic things such as the willingness to be healthy and motivated are decent measuring sticks of happiness as a starting point. It can be impossible to be truly happy solely through means of finances, but it sure is a good place to start.
Merriam-Webster has several definitions of happiness, including prosperity, good fortune, and contentment. If someone is unable to feed their family or live in a safe home, how would they be able to say they are prospering, have good fortune or are content?
People who are happy are productive members of society, and are statistically more likely to have better approval ratings at their place of work and do well in school. We as a nation should prioritize a better society, and that's why our government regulates things like welfare, and section nine housing.
Money can buy security. Money can buy a full stomach and a roof over your head. Money can buy therapy and doctor's visits. Money can buy safety. Happiness is made up of these things, and many more that can't be achieved before these, and therefore, money buys happiness.