For one, society benefits from it.

You generally get wealthy by providing goods and services to others. The more you satisfy people's wants and needs, the wealthier you get. The wealth means that these people now owe you.

If you accumulate wealth instead of consuming it, you never take them up on it. You are basically acting altruistically - instead you use their IOUs to provide even more goods and services for others (not yourself) by managing your wealth instead of consuming!

I think it is actually an amazing feature of our civilisation. Wealthy people generally don't use their wealth to build massive monuments to themselves - they tend to invest it into economically productive enterprises that make society wealthier overall.

Improving the life of your children, but not - and this is of utmost importance - improving the life of your neighbors children. Because life is a competition.