Money can't be saved without someone else borrowing it, even if that someone is just the bank.

Saving is normally transmuted into investment: spending money on machinery/land/buildings/software development etc that will offer a positive return in the future. Investment counts as someone else's income and therefore increases GDP.

Simply putting cash aside is basically hoarding, and normally loses you value over time unless the economy becomes deflationary, which tends to turn into a disinvestment and unemployment disaster.

In order for the economy to be efficient, production must be consumed at about the same time it is produced; otherwise you have to expend resources to store produced goods, which may be perishable or deprecate in other ways (e.g. technology).

Money, gold, or bitcoin doesn't save any value in itself. If everyone on earth was thrifty and living below their means, the extra value they were saving would pretty much evaporate: bread would rot, clothes would pile up and become moldy, iPhones would become outdated before they were even used. Eventually, the will to produce goes away as you can't sell all of what you are producing, and an equilibrium is reached where you live about at your means: if you must save for future expenses, this is only possible if someone is spending more now via a loan.

This is why China being a country of net-savers is bad, and a push for social or mandatory health insurance is a good thing: people don't need to save themselves for medical emergencies, and can instead consume. But until then, the ability for the Chinese government to lend money to someone reliable (the USA), is quite useful as there is a good chance they can effectively draw on their savings later.