Copypasting Bitcoin code is not as easy as it may seem, and even if it's done more or less correctly, such coin is not getting any popularity. So most altcoin creators either make Ethereum tokens or create a new codebase for their coin, even if they heavily borrow the design from some other coin.
Copypasting it is easy changing the parameters to make it look like it is different from Bitcoin is a little more difficult but anyone with a small amount of programming knowledge should be able to make the changes without breaking anything. If you go to the altcoin board you will see that this is common and most people copy the code and then replace the name and total supply with their own but they are not different from any of the other 100s of altcoins in that board except for their custom name and total supply. They are never successful but it does not stop people from trying.