A man was walking along the beach and saw another man fishing in the surf with a pile of crabs beside him. As he drew closer, he saw that the pile was full of live crabs.
"Why don't you put them in a bucket, so the crabs won't escape?", he said.
"You don't understand.", the man replied, "If I put the crabs in a bucket, they might crawl out."
So it is with people ...