Any hand is an all-in preflop or a fold preflop depending on the situation.
Example 1
You are in BB and look down at 72o. You only have 2,4BB left, and someone has raised to 2,5BB. The pot will be 5,5-6,5BB depending on the ante, and its only 1,5BB more for u to call. For that reason you should go all-in, because you are getting the right
odds, even though 72o is almost certain to be behind.
Example 2
You are in BB and look down at AA. You have 12BB left. Its the bubble of a satellite. Someone with a 13BB stack has jammed, a 4BB stack has called, and a 29BB stack has also called. Then you should fold, because its very likely, that you can cash by letting them bust each other.