Is it permissible for the financier to take a profit in exchange for his contribution to financing the purchase of land, whether it is sold or invested?

The apparent meaning of the money changer's statement is that he participated in the land, not that he lent money. Therefore, he has a share of it proportionate to his capital's percentage of its price. If it is sold, he gets his share of the sale price, whether it increases or decreases. If it becomes stagnant and is not sold, he only has his share of the land.