While it's true that some coins, especially rare ones, can fetch hefty prices at auctions or from collectors, the value you've mentioned for a Bicentennial Quarter seems quite exaggerated.
Bicentennial Quarters were minted in 1976 to celebrate the 200th anniversary of the United States.
While they may have some value to collectors, it's highly unlikely that one would be worth $1 million USD.
Typically, the most valuable coins are those with minting errors, unique historical significance, or extremely low mintage numbers.
This coin is one of the earliest minted by the United States and is extremely rare. In 2013, one sold for over $10 million USD.
Designed by famed sculptor Augustus Saint-Gaudens, this gold coin is highly sought after by collectors. One sold for over $7 million USD in 2002.