The definition of acceptance is to realise the reality of a situation and be at peace with it. When you break it down like this you can see it's not an over night flick of a switch. For example living with pain requires a level of kindness to oneself and an ability to be with things as they are to move on and carry on in life.
Please before you pass judgement on anyone's quality of life, stop and think. Don't just claim "I couldn't cope", as I really think you could. Pain, like many other trials in life, can be beaten. It can be medically treated and psychologically mastered, with help, and so we need to have a sensible debate on quality of life before we go any further down a road that may be very hard to come back from.