Do some research on how most smokers die and the amount of suffering they have to endure before they die.
This alone should give most smokers a very strong motivation to stop smoking.
If you have been smoking for many many years, then yes, there is no point to quit as the damage has already been done.
There is so much wrong in this post. Studies have actually shown that quitting by a certain age (sometime ~30) means you can reverse the damage done to lungs. And honestly, the fear mongering stuff doesn't help all that much.