Can we still say we are gambling if the event is something we are at least 90% sure that we are going to win?
Of course. There are many gambling events and games where you have 90% winning chance, however, the money you put at stake will guarantee only a small amount in case you win. On long term it's not profitable anyway, as the house still overcome gamblers, because for each loss you face (inside those 10% chance against you), you have to win another 10 bets just to recover the lost money previously.
You may have 99% winning chance and it will still be gambling, and potential profit will be always proportional to your winning chances. The more winning chances you have, less profit you will potentially make.