To 'want' is a painful thing; to 'need' is a joyous thing.
Only a fine line separates 'want' and 'need'. Sometimes, what we want is not what we truly need. Indeed, there are many things that I want to have, but after careful consideration, it may not be a must to have them.
To need is not a sin; to want is not entirely a sin either. If I were to want something and upon getting it, share it with those who need it, then it is the need of others and not mine. Of course, I am allowed to want something that 'I should have'. What does this mean? It simply means that it is something that I can expect to have.
For example, do you deserve to have the salary you are getting? Many people do not consider factor like their abilites, positions and the general environment. They strongly crave for what is not allowed, and this becomes something of great distress to them.
The problem with people is that they want too much but do not really need a lot. Wanting too much will result in insatiable greed, making one a slave to material goods and plunging one into the abyss of suffering.