Disagree. While expansion overall might be zero sum game, there are definitely positive plays to be made. USC in the B1G is an example. So is Texas in the SEC. And so on.
USC and Texas are different kind of brands than say Clemson (or even a Miami). Clemson and Miami are brands who were built on a run of success.. as that success fades so does their star (Miami's star is much dimmer already than it was in the 80s and 90s; even in the early 00s). Texas & USC have the generational success that allows them to weather mediocrity and still retain name value. In addition, they also opened new home markets for the broadcast rights of their new conference's games. Neither Clemson, nor Miami do that.
The ACC has one school football-wise that you'd consider a Texas type brand. That's Florida State. Clemson is on the next tier (due to the recency of their run) and Miami just below that. I don't think you'd find a network clamoring to pay Miami a full-SEC level share as a member in that conference. UNC is probably the third most valuable brand given that it opens a new and growing market and features major generational brand identity (primarily because of basketball) despite football mediocrity.
Ultimately there are positive plays to be made. Just not enough positive plays that if the SEC says they need 4 members that ESPN is going to go out their way to help the schools break the GOR (and it's more far-fetched as some have suggested that they'd keep the leftover ACC whole to help FSU, Clemson, et al avoid litigation for damages should they breach the GOR) to get those members to the SEC. The subsidy that they had to pay to put Miami and say Virginia Tech or NC State as teams 3 and 4, would outweigh any added value from Florida State and Clemson. Plus ESPN can already air Florida State and Clemson at a discount and can get more value out of a higher rated team in a playoff matchup that they own the rights too (say as a 12-1 ACC champion) than if they are qualifying as the 8-4 8th seed. ESPN certainly has not interest in helping breach the GOR so that Fox can add value with UNC and UVA.
My stance isn't that there isn't value to be had in the ACC schools... it's that there isn't enough value to guarantee a P2 landing spot for the number of schools that would be necessary to kill the conference (and at some level Notre Dame gets a vote (and while they have a landing spot, they'd prefer not to use it), which makes the leftover 7, a leftover 8). No school is voting to nuke the GOR and then paying exit fees for a lateral shift to the current Big XII.