In fairness to the Hornets, what success looks like for every team is different.
The reality is that they've been god-awful for years now. Even when Kemba was there. In the last decade they've won more than 40 games only twice, in the East. For comparison, they've had 3 seasons with fewer than 30 wins in that time. They're just awful, have been awful for ages, it's bad.
For them, they've got some good players now. They have PJ Washington, they've just drafted someone they hope can be special in LaMelo, they have Miles Bridges and Malik Monk and Devonte' Graham.
Adding Hayward, they're very possibly a playoff team this year. Just achieving that for a couple of seasons is probably a big win for them, and it gives their fans reason to watch, and by the time they have to extend Washington and (possibly) Ball if he ends up being good, Hayward's deal will be expiring.
No, paying Hayward essentially $40m a year is not good. But for them, with nobody going there otherwise, it's that or miss the playoffs for another 5 years arguably, so I get it.