If I write a book, compose a song, what's to stop you from taking that and making money off it?

Nothing. And that's a good thing.

If you build a gizmo you have the right to sell it or not. If someone comes and takes your gizmo without your permission and sells it, that's theft. You would be upset about that.

Yes, because depriving me of real scarce property is theft. Copying is not theft. Value is subjective, and cannot be considered an inherent attribute of any object.

Even worse - if you made a gizmo and it was the best gizmo. this is the gizmo that is finally going to lift your family out of poverty. You are finally going to be able to live the life you want to live. you show it to your neighbour, full of pride that you will finally succeed. Two days later your neighbour starts a company manufacturing and selling your gizmo. He makes a bundle of money. You make none. You missed the market. Yours is not the 'original' gizmo so no-one wants your gizmo.

This doesn't happen. Like, ever. Even if it did, no real harm has been done. If he can reverse-engineer the gizmo and manufacture it over such a short time span, that's HIS PROPERTY and HIS GENIUS.

The argument that you can't own ideas is interesting. 'Ideas' is a bit broad and a bit mis-leading I think. While the patent system is certainly misused to lock concepts and ideas down for future profit, when I talk about intellectual property, i'm talking about things like writing, music, art, invention - things that are made via hard work, talent, insight.

The use of the patent system to protect the inventor / artist and allow them the time to profit from their efforts, I think is appropriate.

Opinion is not argument. The sales pitch justifying wrongdoing is not an argument. The fact is, the patent system enriches the corporate fat cats and has been designed for that purpose from the beginning. It bankrupts the small players who try to use it, and bankrupts the innovators who can't lawyer p to protect themselves from fraudulent or abusive IP claims.