Once you paid for something that could melt copper, dime, nickel, and depending on the age of the coin, silver....then you'd tank all the profit that you would get from melting them all down. Short term, at least.
This is why I spend paper money and not coins.
The metals that make all coins are worth more than their face value.
If you melted down all of your coins and separated the metals, you'd have more money in metals than you started off with in coins.
Spend your paper money before everyone realizes it's worthless or trade it in for coins.
Or be like me and have no worries.