Money is like health and love: an energy source that can help create an easier and more pleasant life.
You may have lots of money because you worked hard for it. You may also be in excellent shape because you work out. You might be well-loved because you worked sacrificially on behalf of others.
Then again, you may have lots of money because it was given to you. You may be in excellent shape because of good genes. You may be well-loved because of your charismatic personality without having done anything virtuous or admirable.
And, it's very possible that hard work won't lead to more money, or a better body, or the love of others.
You might deserve what you want, but not get it. Others may have what you want, without ever "earning" it.
You can resent them, or be happy for their good fortune.
What's the benefit of resentment?