Let me be clear - DO NOT BECOME A REFUGEE! It is imperative that you fortify, stock, and prepare your home to be your Bug-In-Location (BIL). Leaving the comfort, shelter, security, and supplies of your home must be a last resort.

I am going to reiterate: DO NOT BECOME A REFUGEE!

Survivalism is a lifestyle, and as such might require you to relocate from that high-rise urban apartment complex to at least a semi-rural suburban area. Your home is your castle, and choose it wisely!

There are literally COUNTLESS reasons why you might be forced to "bug-out" of your home. Fire, flood, civil unrest, tornado, earthquake, biological agents, nuclear dirty bomb, toxic pollutants from a train derailment or nearby factory burning, etc. etc. etc. If you are FORCED to "bug-out" then what do you really need to take with you?

KNIFE
FIRE
SHELTER
WATER
DEFENSE
FOOD
MEDICAL

The seven topics above are necessities to survive in ANY ENVIRONMENT. You must be able to make fire, purify drinking water, avoid exposure (hypo and hyper thermia), replace lost calories, treat wounds, and lastly protect yourself from people and animals.

Since you have to be prepared to carry all of your gear on foot - you have to choose the gear you have carefully. The propensity for "preppers" to focus on gadgets and superfluous gear is another reason why the "72 Hour or 3 Day Bug-Out-Bag" is so popular. However, an average person can carry far far more supplies than 72 hours if they really understand what a "Bug Out" is about.