I would like to ask why One Piece is called ONE PIECE?

About the meaning of ONE PIECE (from comic fans)

[O]vercome myself——overcome yourself

[N]avigate the reticent companion——on voyage Silent companion

[E]ager for the historical fact——longing for the truth of history

[P]ursue the most of dream——pursuing the biggest dream in the world

[I]nsist on promise——stick to the promise

[E]ntertain a belief——have faith

[C]onfront the life——face life

[E]mbrace emotion——Embrace emotion

This is Baidu Encyclopedia’s explanation of Onepiece

I believe that Onepiece is not wealth, but may represent a belief. Friendship among peers. Because One Piece is not about how they found this treasure, but the adventure between them and the process of fighting for their dreams.