Djed is not like Tether or USDC coins. Djed uses only one external output, which is the price of the peg. All other functions are done on a blockchain. So when you buy Djed you have to pay with ADA. That ADA is held by Djed DAO in a ratio of the peg plus fees for reserve. That means that Djed removes ADA from circulation and holds it in it’s reserves. If you sell Djed you get ADA back at the pegged ratio.
So if other markets adapt Djed from Cardano network then everyone buying Djed on any exchange or platform will be increasing demand for ADA. If Djed become as widely accepted as Tether this will make ADA one of the most relevant crypto in existence. Basically you would have to lock up ADA in Djed anytime you want to by a Bitcoin. That sound relevant to me.