Everything is designed to make you spend more and more money. E.g. the award for a week-long event gives you an award to make your plane more powerful but with only 1 HP. Obviously no one wants that. And on top of spending tons of gems on the event, you now need to spend even more gem if you don't want that award. Also the dev have abandoned the game since 2019, just some empty update to keep the game in the app store.