right  !  if you get a direct hit on your roof  . but 

Lightning  can  get in your  house via  many ways

power gate
garden  lights
Astro dish
TV  antenna  on roof
telecom  fix line phone ,  streamyx  line
Mains power line .

So you need  install  some form of protection  for your Devices .  those expensive ones.

1.  an    easy  NO cost  way  is to UNplug  the devices from the mains .