If Facebook is satisfying you, it is not called as time wasted. Full stop. If the purpose of time is your satisfaction, and if doing all kinds of nonsense on Facebook satisfies you, then you cannot call it as wasted of time.
The only thing that determines whether time or money or any other resource available to you is wasted or properly utilized, is whether it aided your liberation. Anything that contributes to your liberation is a thing well utilized. Anything that impedes your liberation is a thing badly wasted.
If Facebook can contribute to your liberation, Facebook is great. But if on Facebook you are just adding to your nonsense, your conditioning, then obviously it’s very wasteful. And the blame does not lie with Facebook; the blame lies with the use you are putting Facebook to. Amongst you, there might be a few who might have found me on Facebook; Facebook is wonderful for them. Or, you could also access all kinds of trivia and rubbish and nonsense and porn on Facebook.