I’m not quite sure you understand the importance of the patent system to the inventor who goes through a very long and expensive process to get a patent, this is not the same as filing a copyright and generally takes around $20K for patent searches and filings. There are companies that steal inventions and a lot of the screaming about patent trolls comes from those who have no interest in the patent system like open source software devotees. So either you believe a patent is property just like real estate, and if someone builds on your real estate it’s stealing, or you don’t believe it’s property in which case you’ll have to argue with the constitution since the Patent Office is established in it.
As a more layman explanation of the protection the patent system, offers you can read the story of Robert Kearns who invented the intermittent windshield wipers on your car, http://en.wikipedia.org/wiki/Robert_Kearns. The auto companies wanted to steal his invention and he had to fight them. Was he a patent troll because he wanted to be paid for his creation?
That is not what a patent troll is.
The constitution only gives Congress the right to establish monopolies. It does not make those monopolies property.
Your argument in favor of government monopolies is that anyone who spends a lot of money should be guaranteed a return. What system of property rights is that?