in times of an epidemic, everyone fleeing to a safe haven at the same time, carrying all their (hidden?) ailments with them, does not seem safe at all. what happens? the safe haven is no longer safe, and it is now overcrowded to boot. then the prior, permanent inhabitants and owners of the haven say.. shoo, go away, you’ve messed up our front lawn (or our exchange rate, whatever).
hmm.. maybe a sheep analogy would have been better. too many sheep in one pasture.