If 15 traders with 7 listed with a profit of 1 mana or more would mean the % chance would not matter it would resolve no as % chance cannot exceed 15*7=105%.

Once a trader you can't cease to be a trader and once you have a profit you might not willingly change to a loss situation, but if you have a significant position perhaps a big movement might cause a profit or loss to reverse. There is also possibility of being bribed to give up your profit through some trades.

If the calculation doesn't reach 100 then a whale might push it up or down in last seconds to make a profit. (But will that change how many make a profit?)