Store of wealth is actually a "bad" function for money. That's what "wealth" is for.
Money is for transacting, a unit of account, a medium of exchange. Something easy, and usually fundamentally valueless. Contracts and debts require an inflating base for the debtors to use, and it's better for the savers to simply save in a different unit than the "common" money.
Wow. So unless you run out and spend every dollar you earn - you are doing something harmful? No.
Choosing to Not spend your money is an individual's choice, and, saving instead of spending part of your income sends a message to the market about the condition of the real pool of savings/wealth available.