Politics always plays into arms sales. So does economics. So does logistics. Also, whilst the aircraft won the competition, the competition is not inclusive of all things an aircraft may be required to do - so, nations that have needs not met by that aircraft wouldn't be buying it - i.e. if you have long coastlines to cover, you don't want a short-legged interceptor. Likewise, if you're planning on running escort missions, interceptors are a bad idea - you want an air superiority fighter. OTOH, if all you're looking to do is defend a few well defined high-value locations, then a short-legged, high-speed interceptor might be exactly the ticket. Maybe your defense budget is limited? Then you want a multi-role fighter to cover as many jobs as possible on one airframe.
Why wasn't Fiat more successful at selling warplanes? There are likely a whole host of reasons, and politics I'm quite sure is on that list.