There is a difference between making 2.5 billion because you owned stocks and the market went up and making 2.5 billion because you bought just before the market went up and then you sold.
It's unlikely you can make 2.5 billion with a single unleveraged trade. The market went up by what, 6-7% that day? Nobody bets his whole net worth on this to make a profit like that. So I think leverage was definitely involved, which just shows that insider info was definitely there.