wow, just wow. Go slap those people. Yes it does take power to make power. Think of it like this. In a perfect world, adding a supercharger would add, let's say 100% more power. Now, to the real world. Yes it does take power to make power, but not from the same area. Let's say X brand supercharger will add 100 percent more power, but 25 to 30 percent of that power has to be used to turn the blower to make power. You are taking power to make power, but the power that the blower makes is more than what takes to make the blower turn. So with this X brand supercharger, you are still gaining 70-75 percent more power.
Hope that helps.