Not if his 7defeats happened when
1- He was a rookie
2- He was facing an army of powerful combattants
He is a pirate since 20years at least. Someone like Luffy already has more than 5defeats in his single year as a pirate and he'd be pirate king. It's through defeats that you learn, gain experience and become stronger and he was facing yonko and marines a lot of times and still survived, which shows his great combat experience
We know for a fact that he wants to die and has the personality to face huge armies without caring. It won't even surprise me if he faced Red Hair Pirates alone 2 years prior
The fact he mentioned WB during his introduction though seems to imply something happened between the 2, especially since he tried to target him before he faced the marines.
1- Maybe he just realized WB was the only one who could kill him
2- Maybe he wanted to participate the great war alongside him(to have better chance to die)
Among pirates Shanks at this point is only option that can come closer to being able to defeat him.
Depends if Kaido had that title 2years prior or not. If he did, maybe. If not, Shanks can't win by himself