Crocodile and Doffy are richer. Croco is potentially a billionaire.
Doffy ran Dressrosa and business with Kaido but fact is his main business/cash flow was from Kaido given SMILE factory and Caesar so it cannot be more than Kaido’s business himself which was selling weapons, BM surpasses Kaido in wealth
BM has deep connections in the black market and best intel network, everybody comes to her tea parties, the sweets she demands to be produced alone rival the best riches of FMI, tens of thousands of fleets, an entire country’s worth of GDP, and her theme is based off of mafia family so she def has a several businesses at least as many as Doffy, possible Doffy and Croc combined
Even if 75% of BM’s assets come from sweets it’s the capital required to produce those sweets that give it their worth and FMI was running on fumes producing those sweets. So those sweets are worth another country’s GDP
She also has other territories to demand compensation unlike WB and Shanks who just let countries do whatever so that adds to her wealth too
Her commanders/children actually had full-time jobs and valuable capital-intensive skills, formed political connections with other strong families, in addition to fighting strength unlike most pirates
