First, please take note that this is the rambling thoughts of a person who spends all day driving alone delivering people their stuff.
It’s not just the money. It’s what the money represents and the act of getting the money. People strive for success. In western society success is a combination of stuff and (to quote Charlie Sheen) winning. So, a successful person has the best stuff which requires money. Also, the amount of money a person has is a measure of that person’s success and importance. The richer you are the more important you are (think Kardashian).
Money can also buy power. Many people strive to be or feel important. That is why the internet (chatting, Facebook, YouTube etc.) has exploded.
Money makes life or at least money makes life easier. Food, transportation, housing and more improve with money. Money can’t buy love (just rent it) but, it can facilitate happiness (even if that happiness false).
I live in the US. You can’t live in America without any money. You can’t own a car, house or even live free (thanks Obama) without money. In our society, the homeless are almost considered subhuman or at the very least unimportant. I always thought it was interesting that the wealthy are offered free stuff while the people with the least get nothing.
Beyond this it is hard to be specific because everyone has a personal motive.