I don't know how it works in Spain, but under U.S. law, when you buy a car (or a CD, or a book), you own the physical product. However, you do not own is the text of the book, or the song itself. Those remain the property of the artist, author, company, or whoever holds the copyright.
What you pay for is the right to use that product, in the form of a physical item. That has been legally construed to include the right to reproduce the product for your own use.
Like I said, I don't know how it works in Spain, but what you are doing violates copyright law in the United States, where WotC is based. "Economic harm" is not a relevant criteria in assess the violation of copyright law. WotC owns the work. You do not. Nor does someone who bought the book. As such, owning the book (or pdf) confers no right to distribute the product to others. With ONE exception. You may choose to distribute the physical product to others, by sale or gift, but only once. And you may not (legally) keep a download or scan if you do so. That is, unless you have paid WotC, or one of its authorized resellers, for said download or scan.
That's the law. You may quibble with it. But that's U.S. copyright law.
To be fair, the United States has stricter rules on intellectual property than many other countries. Preserving ownership over what you create is intended to encourage innovation and creativity. I take it you believe this is a bad thing?