Many smaller 'airports' have sideline businesses, many airports have reduced costs allowing them to survive with smaller passenger numbers.
Some airports have owners who see the airport as a means to provide a more lucrative business.
Some airports have extensive non commercial facillities.
And from a previous post....
This is the right thing to do, but whether they are going about it the right way is a different discussion...
As I hinted before, the main problem with most "at risk" airports is not that they cannot exist profitably, but that their owners/managers either cannot identify the activities that they are uniquely suitable for (eg heavy maintenance, cargo, training) as their core business, or that they can do that, but haven't got a clue about how to configure and market themselves to attract those businesses.
This is because in many cases the owners and/or management have little or no real in-depth knowledge and experience about the air transport industry.
NQY is a case in point; if ever a priceless asset was thrown away it is that sorry place. Cornwall CC were about as bad as it can get as owners, and their incompetence included recruitment of management. I have no idea what the situation is now; those comments are about fairly recent history, not necessarily the present day, so please don't sue me! Unless you are CCC, in which case I'm happy to prove that what I said of that recent history is absolutely correct.
Other airfield managements are still in the dark ages about the partnership nature of their relationships with customers and users. I'll bet you could still find operating airfields where you can only rent space for your aviation-related business on 5-year fixed leases, full insurance and repair. This dreadful inheritance from public ownership days is the Holy Writ to some owners.
It's managers that kill or grow airfields; an operating licence is a priceless asset that can
always make money once the owners/managers recognise their unique strengths, and focus on that while ignoring fantasies about having zillions of passengers.
Afterthought: The other great destroyer is the ill-informed but influential, wealthy and hypocritical NIMBY opposition to any proposal for commercial airport development. I would cite Bentwaters as the perfect example of how a few such people managed to prevent its re-opening as the primary heavy maintenance base in the SE of UK. They did this by a mixture of outrageous lying, distorted and dishonest assertions, and lying blatantly while giving evidence to a public enquiry. As a result, 2,500 high-skill, high pay jobs were not created in a deprived area where the black economy ruled to service the wealthy, for which the environmental impact would have been virtually zero.