Because he said "profit". So take away the £1m we paid for him, giving us 1.5m. Then take away the 15% sell on fee due to watford.
Though, that actually leaves 1.275m profit, not 1.25m. But then there are the wages we paid him over the course of his time with us, so did we actually make any profit?
We still didn't 'sell him for £1.25m' which is what he said.
And adding in the wages to the calculations would be daft. If you were going to do that, you'd also have to factor in a share of all the gate money, prize money and commercial income the club made whilst he was a member of the team / squad.