What it means is that once you're up there, you don't need much by way of outside investment unless you're really going all out to challenge the top four (which not many clubs really fancy, they heed the example of Leeds, although they did it through leveraging which has its own risks). You can own a club, it'll produce a return, give your businesses exposure if you have other interests and you don't have to fund it too much. Whereas back in the day, you could only afford big signings if the board pressed the button, preferably if you had a really rich guy running the show. As the owner you can cream off whatever percentage you like, with whatever knock-on effect that has on the team. Mike Ashley doesn't fund Newcastle. The Glazers don't fund Man Utd. Lai doesn't fund West Brom. The Pozzos no longer have any need to fund Watford. And so on.
You don't really accelerate miles ahead of Championship teams forever more. You can buy expensive players but they aren't going to stay if you go down. You can't really replace them either. You won't save the money that TV income brings because you'll just go down, so it all gets spent one way or another.
The easiest way to think about it is if I earn £20k a year and have £5k worth of bills a year, and you earn £100k a year and have £85k worth of bills. You should be miles richer than me, but you aren't. You have nicer things for now - which the £85k pays for - but if you lose that £100k a year job then they all have to go and you need to replace them with stuff befitting your new, much lower salary.
