A Crimson Trace laser is an excellent training aid. It also serves for older shooters whose eye sight is not what it used to be. And lastly, if you are out of position (say you were pushed down) you can draw and sight without bringing the gun up to your line of sight. If you ever engaged in real life combat or defensive training, the value of a laser sight becomes very clear.
Also, consider that the most dangerous time is at night and that scaring the perp is better than shooting him (legal defense is very expensive). Ask any combat vet....killing someone is not something to take lightly.