It's not just some money it's insane amounts of money and even then you can't always do it, for example because you cannot own slots for flights you don't actually operate. Those revert back to the airport and get sold to someone else.

There is always a way but never enough political and actual capital to do this. You could build your own airports, buy other airlines but you run the risk of losing the spot if you don't actually use it.

The cost would be so high tickets could double if it was even possible.

Airlines, especially post-deregulation, operate on razor thin margins.