He's a sure thing to sell shirts, to increase our sponsorship deals, to excite the fanbase worldwide, etc. If he doesn't perform, he'll still make news, divide opinion on MOTD or w/e, which in turn will put us in the spotlight and drive our popularity even more. If he does perform, even better. Either way, we're golden. Any club with our resources would love to spend that money, we've just been too foolish and refuse to play the game. Football is cynical, it's time we grew up a bit. You only really get there by bringing in big money players with global popularity. Aubameyang and Ozil are a start, but they just don't have the same cachet.
Otherwise, we'll just have to be content with living at our level, and maybe picking up a trophy against the odds now and again.