"At that time, there were very few loofahs available in the Fuyang market, and we accounted for a large market share.

I add "available" because it makes it clearer that you're talking about what's for sale. It does work without it but "in" could be ambiguous for some items. You could also say "few loofahs on the market", and that would explicitly mean for sale. And I changed account to past tense because it sounds like this was in the past?

It's not clear who "we" is. Ma Tao and his business partner?

This also gave Ma Tao an inspiration - if you have a single product is done extremely well, you will have the right to speak and bargainbe able to promote it and bargain effectively in the market, and the profit will naturally be high.

I can mostly guess at the meaning here, but "to speak" really doesn't seem to fit. And passive voice here is grammatically correct but strange - it's important that *you* do the product well, because *you* will be the one who benefits from it. You don't benefit from a product being done well by just anyone.

So I rephrase quite heavily.

Ma Tao, who has culture and good manageeducation and business acument, quickly earned the first 500,000 yuan and the first 5 million yuan in his life in Yaohai Agricultural Products Wholesale Market.

Neither "culture" nor "management" really seem to fit here, they sort of make it sound like Ma Tao is a company, an institution. I suggest the kind of things I might say.

Nothing else incorrect, but it's unusual to mention the first 500,000 and the first 5 million right next to each other like that - if he earned the first 5 million, then of course he earned the first 500,000. If this is just for effect it would work better with more structure: "he earned not only the first 500,000 yuan of his life, but also the first 5 million".

And I would probably put "the" before the Yaohai Market, but it's okay that it doesn't have one. We just often like to have a "the" before places that are named like that, just some adjectives before a regular noun.