"Humans still need to eat and stay warm and fulfill their daily needs in a deflationary environment."
EDIT: to add onto that answer, I'd say that just as there are still savers in an inflationary environment, there will still be consumers in a deflationary environment. Incentives matter, but are not absolute drivers.
If you said "It is counter intuitive with Keynesian economic theory", I'd see your point a bit more. But different schools of thought like the Austrians view the importance of short-term consumption differently than what is a sort of textbook model of the world.
EDIT: to add onto that answer, I'd say that just as there are still savers in an inflationary environment, there will still be consumers in a deflationary environment. Incentives matter, but are not absolute drivers.