Civilisation collapses for whatever reason. You can't rely on supplies like gas, batteries, electricity, medicine etc. You may have supplies, but eventually these will run out and you will have to hunt and forage.

You have to be able to move fairly quickly to deal with changing situations. You have to be able to stay /out/ in winter in Northern Europe/USA, but also stay cool during the summers. You may be able to use buildings for shelter, but there is no guarantee and you need to be prepared to go into the wilds for extended periods to avoid raiders, mobs of zombies etc.

What is the best forever kit?

>Moving kit (hiking/running, hunting)
>Camping kit (keeping warm when still, being able to rest)
>Tools/equipment
>Ideal baseweight
>Weapons