Yes. Why not? If you steal my bicycle, I can't use it anymore. If I steal your idea, you can still use the idea. Only one of us can use the same oven to bake a cake but an infinite number of people can use the same cake recipe.
If i write a book, I spend time, effort and resources on this process. I need to recoup those expenses + profit. If you copy the book, I get no return on investment. If you copy the book and sell it for profit, I can't compete against your price, because you didn't participate in the original expenses so you can reduce your margins. Think about it with a movie. Lots of money spent on it, jobs to pay, places to book, stories to write, film to edit and god knows what else. If you take it for free, I am losing money in the process, and I certainly didn't make that movie to lose money. If you steal my movie, I can't pay for food or rent anymore, how's that?
But let's discuss the fundamentals: do you think intellect can consist in property?
People write for free all the time. You and I are doing it on this forum. Wagner and Beethoven composed before copyrights. Did it impair their creativity? There is no such thing as intellectual property. It's an artificial commodity no more legitimate than carbon credits or Catholic indulgences. Comodities have to be scarce (not in infinite supply). IP requires FORCE, aggressive, initiatory to remain scarce. That's immoral.