Free markets are not free of coercion, they are just free of regulation. You can still dump shares, create ponzi schemes, perform insider-trading, double-selling, market manipulations and construct monopolies in a "free" market (unless the market is infinitely big and has infinite liquidity, but in real life that doesn't happen).
You are forcing others to pay for your idea, while they might have come up with the same idea by themselves.
No - you are forcing them to pay for using your idea (with emphasis both on using and on your idea).
The patent system discounts the possibility that someone else came up with the same idea because for an idea to be patentable it needs to be
* A new idea (you can't claim permanent ownership - only temporary ownership of it)
* That you invented (i.e. it can't be public domain)
* Within certain restricted fields (e.g. you can't patent musical sequences)
* An invention (you can't patent abstract concepts like minimalism)
* Non-obvious to an expert in the field (which in practice is the experts brought out as witnesses by your competitors during trial - not patent office lawyers)
* Stand up to scrutiny in a court of law.
So since nobody else came up with the idea themselves, you are strictly only preventing people from taking your ideas and selling them without your permission.
If you take away the patent, how much is the idea worth? Nothing.
How much is a guy worth that comes up with ideas? He's priceless,.
Without patents, he is a guy who comes up with lots of ideas which are worth nothing, as you just clearly pointed out. ie. he is worth nothing.
Let me just put it like this.
If I were head of Microsoft and the US decided that patents were illegal, I would immediately fire everyone in the research department and start up a big department of people to reverse engineer my competitor's products. Because research is expensive and without patents it's much easier for Microsoft to wait for small companies to come up with ideas, then quickly copy them, slap a Microsoft sticker on them and watch all of the small companies go bust because Microsoft's sales department already has contacts in all of the firms that matter, because Microsoft is a trusted brand, and because Microsoft is pretty good at printing CDs already.
Or to put it another way, if patents were illegal, it would be much cheaper for Microsoft to be innovative by forcing small innovative companies out of business than by bothering to do research.
And then what would happen is that all researchers and research companies would leave your country and go to a different country where they can make money from doing research. And very quickly Maddus Mattus, your wall in Berlin won't be able to keep the population of your country from fleeing your borders and ... oh wait, this has already happened somewhere before?
How did that regime that thought ideas belonged to the people and that people shouldn't be rewarded for their talent or hard work turn out in the end?