Bezos worked in finance (hedge fund) before starting Amazon. He was not a VC.
A perfect example of finance domain knowledge.
But I don't think we can attribute it to finance domain knowledge.
To call Amazon a bookseller is missing their entire raison d'etre. Bezos wanted to be King of Volume, and how much of their current revenue is books? Can you imagine Barnes and Noble starting BNWS?
As a hedge funder he'd be looking for secure, smaller returns through diversification. Sound anything like Amazon's business plan?