Once you figure out the practicalities of buying $100K worth of Bitcoin for cash, securing it, exchanging it for Tether, requesting the redemption, getting paid out to a bank account, etc, you will see that it's not particularly free money.

People who are already set up with crypto accounts, exchange accounts, bank accounts which won't be closed down or frozen, will do this trade all day for 3%. For a regular punter it's not a no-brainer at that level.