Risk is a combination of likelihood and consequence.
In the U.S. it is very unlikely you will be infected, therefore there is a low risk of death from ebola.
Every person from a highly infected area who enters the U.S. increases the likelihood of infection, and therefore increases the risk.
Some politicians seem to think the increased likelihood can be mitigated by reducing the consequence via better treatment.
Why risk the gamble?
The risk of death from walking along a six inch wide steel bar laying on the ground is nill.
The risk of death from walking along a six inch wide steel bar fifty feet off the ground is greatly increased.
The likelihood of a misstep has not changed, the consequences of a misstep have. Risk was increased.
Exchanging the six inch wide bar with a three foot wide bar does not change the consequences of a misstep but it does reduce the likelihood of a misstep. Risk is decreased.
Exchanging the three foot wide bar with a six inch wide bar but installing a net beneath the bar increases the likelihood of a misstep but mitigates the consequences.
Politicians have chosen to exchange the three foot wide bar with a six inch wide bar and a net.
Nets can fail. The carrying capacity of a net can be exceeded.
Do you feel lucky?
Why risk the gamble?
_______________
Because they are playing a game that has not been named.