1. The Sixers can't financially afford to lose Harden to the Houston Rockets
The new Collective Bargaining Agreement could spell doom for the Sixers, particularly as it pertains to the second salary-cap apron, slated to be at $17.5 million above the luxury tax threshold. The Sixers will most definitely surpass that mark with a Harden extension, and especially if it's indeed true that he wants a four-year deal worth over $200 million.
Do we believe Harden wants that? He certainly does, that shouldn't even be up for debate. Harden's max with the Sixers is worth $210 million over four years (roughly $52.5 million annually) and he is certainly gunning for that, after voluntarily taking a paycut last season to help them land P.J. Tucker, Danuel House, and De'Anthony Melton.
The Sixers already have a roster payroll of $117 million, just $17 million shy of the anticipated salary cap (which could change, but not significantly). A Harden extension will put them in the second apron quite easily.
And that's not even factoring in the looming contract extensions for Melton and Tyrese Maxey, both of whom they'd definitely want to keep, whether they lose Harden or not. Financially, the Sixers won't be able to afford to replace Harden, as they wouldn't have the money to spend on a player of his caliber if they lost him.
Granted, they'd be strapped for cash even if they paid him, but at least they'd still have him. It would be much easier to make roster adjustments around a Harden/Embiid pairing than it would be to try and create salary cap space for a player of Harden's caliber after the aforementioned extensions, unless you believe in their ability to move Tobias Harris' expiring $39.2 million in 2023-24.
No contract is untradeable, we know that, so long as you're willing to attach assets to be freed from a bad one. And a contending team would surely rather trade assets to bring in difference-makers and contributors, not just to get off a bad deal like that of Harris.
They also don't want to stand pat in 2023-24 waiting on Harris' deal to fall off, and waste a year of Embiid's prime, who hasn't exactly been able to stay healthy.