Surely survival simply means ‘not dying’, yet for survivalists it mainly means ‘not dying from the wilderness’, and for preppers it mainly means ‘not dying from disaster’.
If you are not going into the wilderness then only train and equip for it if your environment could become a wilderness in a disaster.
In any event, only train and equip for disasters that realistically threaten you. For example, volcanos and armed civil war is not such a threat in the UK as the USA, whereas on our tiny island we are more vulnerable to anything that puts us out of our home such as nuclear war; far from running for the hills, we would have to stay and fight.
Of course, preppers want to do more than survive disaster, they want to cope with disaster, so it is also about maintaining lifestyle and coping with non fatal disasters.
So that brings us to the definition of disaster. Your disaster preparedness has to match what would be a disaster for you. Disasters spread over an area affecting others will probably affect you, but personal disasters are still disasters for you, so you should also prepare for contingencies such as losing your job, home, health or relationship. These are more likely to happen than SHTF and could wipe out your prepping resources or capabilities.
What you need to know before you prepare is what could kill you or turn your life upside down, in risk order of likelihood and/or impact. In other words, what could hurt you?