Of course they can! People can choose to buy only from the inventor, not the knock-offs. As for small inventors, all a patent gives you is the right to sue someone for violating your patent, which is an incredibly expensive course of action from which only the lawyers are guaranteed to make money.

The original idea behind copyright was to allow the ruling monarch to determine what books could be published. That's why the money earned through them is called "a royalty".

And if there were intelligent technologically sophisticated life within 50 light years, it seems unlikely that we wouldn't have received any sign of it after decades of SETI.

From the SETI Institute FAQ:

If an extraterrestrial civilization has a SETI project similar to our own, could they detect signals from Earth?

In general, no. Most earthly transmissions are too weak to be found by equipment similar to ours at the distance of even the nearest star. But there are some important exceptions. High-powered radars and the Arecibo broadcast of 1974 (which lasted for only three minutes) could be detected at distances of tens to hundreds of light-years with a setup similar to our best SETI experiments.

"This add-on is not actively monitored for security by Mozilla. Make sure you trust it before installing." No Thanks!