The cost is so low as to be non-existent. The downsides of printing money are effectively nil. If this were not true the modern global economy would have died out decades ago, when printing money became the primary method of commerce. Your concern here cannot rationally be a concern for printing money, a ship that sailed long ago. So I’d have to assume your concern is how the printed money should or should not be used. And in this case you were replying with concern to a post that recommended using printed money to pay high-risk people a sustainable income when their jobs should be furloughed. But instead of making a case as to why high-risk people should continue to sustain high-risk, you instead want to falsely claim printing money is significantly detrimental.

If this is true then why do any of us pay taxes?

We could just print all the money we need.