I'm sure someone else has posted this but the constant ticket price rises have almost certainly had an impact. As they've crept up and up, it's not been by much each time but it's forced people to make decisions. Even though they may be able to absorb an annual increase, people have dropped Platinum or cup schemes. I certainly did.
I made a decision for a few seasons that I'd reduce my overall expenditure on tickets. I bet others have done this or else have decided to prioritise the later rounds of cup competitions, taking the chance we'd get to Wembley and saving their money for a final weekend. Some just pay for their season tickets and nothing else, and even that's a struggle for them. And by constantly putting prices up, they've not exactly encouraged casual attendees to fill the gap.
Our CEO used to run an airline (which went bust). Imagine an airline that charged £250 for a return flight but that included checked baggage and an on-board snack. Then they decide to charge for those two separately, but don't change the basic price. How many would happily pay for both extras? Only those who had no choice. You'd take hand luggage where possible and buy a sandwich to take on board with you. As the low cost airlines have shown, even charging low basic prices sees people try to cut as many corners as possible. And when you add all the charges up, it's often no more expensive to take a scheduled full-service flight where all the extras are included in the price.
Why go on a cup scheme when you've no idea how much each game will cost or when the club will take the money? Pick and choose. You might pay a few quid more per game but you'll save the money on games you don't fancy, that you can watch in the pub or in the comfort of your own armchair. If the club wants to charge people a few quid extra, via Platinum, give them a discount on a set number of cup tickets, say 50% off any 5 tickets in the first 3 rounds of the domestic cups & CL group stage instead of double points. Then you get money for Platinum and also bums on seats for games that we might ordinarily struggle a bit to sell.
Despite supposedly being a "business" I'm rapidly coming to the conclusion that the people ruining the club have little commercial nous.