People will spend the inflative currency and save the deflative currency, fiat is for spending and bitcoin is for saving, their benefit don't overlap each other. Under a fiat money system, everyone are forced to borrow and spend (savings will lose value quickly), now there is an alternative
What? Under a fiat money system, people invest in an effort to outpace inflation. Who just leaves money sitting in a plain bank account, or under your mattress, doing nothing?