I like the idea that Frank's long game with John was he paid for him to chop his dick off, and now he's in the phase where he's making John hopelessly dependent, and the final phase of his sadistic long-term plan is to dump John and watch him flail around helplessly and eventually kill himself.
That is exactly what a sadistic Fu Manchu level chink like Frank would do.
While we know Frank's an abusive scumbag, and while I would absolutely relish the sight of John falling flat on his ass without a penny to his name, I dunno. There's long games, and there's throwing hundreds of thousands of dollars down the drain over the course of more than a decade. At some point, you'd have to question whether whatever twisted pleasure you get from building up a dumbfuck and tearing them down was worth all that time and money. Like, if that's not gonna give him the best cooms for the rest of his life or something, it doesn't seem like the smartest investment.
But then again...given how John is increasingly camera shy (I don't remember the last time he appeared on video before that TWiT show), and how he's started taking to hat-wearing, his hairline is probably firmly entering male-pattern baldness territory. The multiple plastic surgeries are going to need touching up when they begin to sag as well. If Frank wanted maximum psychological damage, he'd probably want to dump John before another round of surgery or hair transplants, allowing his body to decay before his eyes, without the ability to pay for a crude simulacrum of his "female" face. If John resurfaced from under "Brianna's" skin, he'd be all the more likely to 41%. Just a thought.
And on top of that, most of the things that John has Frank buy for him are things that Frank wants too. They're both manchildren, after all, so all the toys and games that they've collected over the years would still go to good use, just by Frank alone. He could sell off the Porsches at a loss, but he'd at least get some money out of them. The only truly sunk costs are in John's surgeries and the scampaigns.
Regardless of Frank's intentions, John really doesn't know how good he has it. He's so oblivious to his privilege, completely unaware of how he would never find anyone else who would be willing to spend so lavishly on him. But who knows, he might have been better off if they'd never met. Maybe if he hadn't been enabled for all these years, he might have actually gotten the help he needed. Or maybe he'd just be a psycho troon in Denver, I dunno.