Money is meant to be spent, but not everybody wants to spend it the same way.
Creating and maintaining some kind of financial stability is one of the most important factors to having a decent quality of life in the world that we live in, so it follows that two people in a committed relationship should try to have similar attitudes towards this. Being with somebody is all about building something that makes things better for both of you, especially if you are married.
One of the most common sources of disagreements between couples relates to finances, and not always because someone is spending too much money. Things can also go too far in the other direction, with people being reluctant to spend even if it makes sense to. While it is important to take care with personal finances, too much caution can sometimes not be worth the savings that it makes.