[The Ace]

It's difficult to deliberately create an anticlimax i.e. a situation where the story just peters out,It's also a very bad move and no publisher would look at you.
The death of your main character need not be an anticlimax, there are many reasons for this to happen;
To give the story realism.
The only way to achieve his objective
Treachery by a supposed friend
A last attempt by his enemies to thwart him (if he's the goodie).
Justice (if he's the baddie).
An anticlimax shows bad writing, a character's death needn't.