You have missed a few important points, most of them are quite hard to know:
1. A lightning rod wont divert the ENTIRE lightning, but it will most of it. Thats why you should get that as well as a whole house power surge protector if possible (even if 1% of the actual strike goes to your home, it will fry everything).
2. In home power surge protectors are only useful against 1 medium power strike or many small ones (these occur constantly).
That means that after a few years, even if your home was not struck by a lightning, you still should replace a power surge protector.
3. Power surge protectors DO NOT help against under voltage.
This is less common but an electronic device that receives too little voltage can be damaged as well. Unfortunately this can only be handled by UPS.
In order for everything to work you would have to have EVERY cable protected and that is virtually impossible, meaning you might be better off replacing your electronic equipment rather than failing to protect it all for a quite high sum of money.
I personally use one surge protector for my TV/PC setup but I well know that the ethernet cable is not protected….
So yeah, the theory is all fine but we still act on human impulses like fear :D.