Characteristics of a business: 1) Customers 2) A product 3) Employees 4) Sales 5) Customer support Sole-trading has none of the above. Thus, trading is not a business. Running a hedge fund, or a mutual fund - THAT is a business. But trading isn't.
1) I sell options to customers. 2) My product are options. 3) I have one employee - me and a subcontractor - my broker. 4) I make sales to people who give me money. 5) My product is perishable & requires no customer support - like the corner ice cream stand. Manufacturing is not the only kind of business. Retailing is another.
I think the Revenue Service would agree with you too especially if you go market-to-market or LLC. Simply, trading is a business although most don't treat their trading as such. Mark