Technology has nothing to do with forever living.
Once you die, you are still living, only that your energy changes from material to spiritual. You become a spirit, and you will continue your journey.
However - a spirit is not invincible. It could die if it's attacked by other stronger spirits. There are rules in this multiverse and guardian spirits that will look after you until you are able to look after yourself.
Just like in life, after you die, you begin a different existence that comes with decisions and risks. Nobody can guarantee you forever living yet nobody can actually state that it isn't possible!
