The 'deathbed' is not a representative state of life. What you desire when you are there might not have much in common with the most meaningful or satisfactory life you could have led.
The deathbed-you has no future, only present and memories.
People on their deathbeds think they know their past selves well, but they probably don't.
They are locked in a time, place and life situation that might be different from yours.