What makes a Guitar Good or Expensive ?

I play Ibanez Gio 7 String and have played my friends PRS (iirc 1,000$) and Fender (player plus blue ocean) and I was able to play a lot easily with them. People say Ibanez GRG is not good.

  1. What makes a guitar good ?
  2. At what point is does more expensive doesn't change the playability or tone ?
  3. I don't get the point of 2000$ Gibson (ignoring the 30,000$ vintage, 20,000$ PRS Private Stock/Fender Custom Shop, 5000$ PRS and Fenders)
  4. Does playability all comes down to Neck Contour, Fretboard Radius, Scale Lenght ?
  5. What makes a Guitar expensive ?