I’m not sure I understand the question, but here is what comes up for me.
As I understand it, to "burn out" implies "burning the candle at both ends " or living as fully as possible, for a short span. I’m not as clear about the meaning of "fading away" but I’ve most often garnered the impression that it has a negative connotation, representing an unrealized, purposeless life that becomes less meaningful as it drags on monotonously..
Many people who "burn the candle at both ends" seem to pay a steep price, often in terms of sacrificing physical and or mental health, which results in a short life. There are also adrenaline junkie who engage in extreme sports and meet early ends. The latter seem to believe an early, spectacular death is preferable to a longer life span that involves a normal slow diminishment of faculties.
Admittedly there are also people born with an above average capacity/energy for achievement/intense engagement with life. They may burn "hot" for a long time without necessarily "burning out". There are also people who are "slow and steady"-- they maintain a consistent pace and achieve a lot without appearing remarkably effortful.
We are each born with a particular temperament and physiology. We have to work with who we are and make the most of it.
If we get to the point where we cannot make wise choices regarding what’s best for our well being, then it’s time to seek professional help.
