We have tried to get them to see the logic many times to no end.
Stop trying, they don't want to hear it and they will get angry with you for trying to wake them up. No matter how much you try you can't care more for their lives then they do themselves. If they are at all open to the idea or see any need for it then they would of already of woken up and be asking you questions about what to do. They have already told you that they are not interested. All your pounding away at them will do nothing but drive a wedge into your relationship with them. But I do think you need to find a nice way to tell them that you have tried to get them to see the need to get ready to take care of themselves but because they have rejected your advice that when the bad times to happen you will not have sufficent to take care of them. While they have been spending their money on vacations, cars, trinkets and toys they don't need you have been watching your pennies and putting away for the future. The reality of the situation is that you can't do for them if they won't lift a finger to do for themselves. In order to make yourself feel better put away a pallet of basic foodstuffs for them and when the bottom drops out give it to them and tell them they are on their own.
"Christianity began as a personal relationship with Jesus Christ. When it went to Athens, it became a philosophy. When it went to Rome, it became an organization. When it went to Europe, it became a culture. When it came to America, it became a business."