Except, I'm sure grace DID spend money on food.
Additionally, grace's savings, not spending money on things she did not need, increases net savings and decreases the cost of debt for those wishing to access her capital to invest in things they desire.
If grace went further still and didn't just passively SAVE her money, but actively invested it in things that made a positive contribution or spent that money only on things which made her desired world happen while discriminating against goods and businesses that made the world worse, either to fulfill her own desires for a better world or investing in such for others, she'd actively be choosing to use that money to build up capital in areas of the economy and reward sectors that supplied those things, lowering the cost of supply, and potentially creating employment in those sectors.
Either way, there are generally better things to do than consuming for the sake of consuming. And its primarily not about spending or not spending, but choosing where to spend and choosing where to invest, for an economy that keeps everyone employed but produces nothing of value (or actively produces harmful things) is not an economy anyone should be aiming for.
If we are so far down the path that we are advocating spending and consumption merely for the sake of spending and consumption to keep the economy turning over, then surely it would be better by far to advocate conscious directed spending and investment, rather than consumption.