Saving makes sense in a deflationary environment, its just that "saving" involves letting other people do productive things with the money with rather than starving them of funds in the hope they will be sufficiently desperate for cash in future to be willing to exchange more stuff for it. A deflationary environment sets a floor on how much the 1% control, not a ceiling, disincentivises them from creating jobs (lots of risk, no aggregate money returns to be earned) and makes it risk free for them to starve the economy of resources instead.
And in a world with no "crippling mortgages", you still need somewhere to live before you can save 500k. Which means instead of borrowing and repaying and ending up with a house, you spend roughly that portion of your income on rent instead...