Humans generally have endless needs and feel the urge to get one more so even if you spend all your salary, you cannot fulfill all your needs and desires at once. Life is a struggle to survive people's lives are spent thinking about this and that people have to go to the with some lack or dissatisfaction. Although human needs are infinite not all needs or lacks are the same as people in our society are different people have different needs or needs so it is better to make savings or investment funds to meet the needs of different people. There will be demand but in the meantime building wealth through a savings plan is much less risky and will secure your future and help you build wealth basically, the more money you have the more ways you can use it.
Our wants never end and if we all always key into these needs then it now becomes a problem because for you to save and build something for the future of yourself will be a problem. More money comes with more problem and that's just tge essence of life and if we continue to try and cancel all we will find out that actually saving money will be a problem.
Every year there are new phones and if we fuel our wants always then we have tons of phones and it would be useless as we ain't using them or worse you wouldn't have any savings at all.
The more money you have, the more you spend. That is why having the mindset of saving first before spending is best mostly if your income is big so that it is sure that youll be saving some money and not only in wants.