We'll learn about his rise to the top in his flashback imo.
Dude has a serious boner for letting people hit him because he can regen and kinda wants to die anyways.
But i think this happened after he became the strongest.
Given that we know what his fruit is, this could have been a metaphor of him being super weak early and struggling to the top. Once he reached it, he became bored. Because while attaining strength, he still didnt accomplish anything of note like Roger or WB or Oden did.
Hence his desire to die gloriously, and letting people hit him.
That's what i think anyways.