Why is counterfeit money illegal?

How would like for someone beside your partner to come into bed with you and make love to you and you did not know it? Counterfeit money is like that only there is not any thing such as gold in the vaults to prove that the paper money is good. Or maybe you will take checks that do not have any money in the account to cover it. I have an idea, why not you send me something of value and I will pay you with a check that will bounce. That is what people that pass counterfeit money are doing.

Why wouldnt it be illegal? Thats basically like getting money for free. If your thinking about trying it i wouldnt do it. Its not worthy going to jail over.