By colonizing the moon humans would be expanding their knowledge and also their horizons so that they can learn more and be better prepared. I also believe that colonizing the moon will help to keep human existence alive. If a drastic event happened on the earth the humans on the moon would still be able to survive and flourish.
Colonizing the moon isn't healthy for humans because it takes funding away from feeding, clothing and housing those people who need basic things to live on Earth. In terms of permanent moon colonies, bones and muscles on normal human bodies will atrophy from a lower gravitational field on the moon and the physiological systems in humans will alter.