The early raids were typically driven by TV contracts. ESPN had signed one with the ACC, and the Big East was going to be negotiating a new one in 2004 or 2005. The Big East was coming off a bad contract because Miami had been in NCAA enforcement purgatory when the Big East negotiated the deal from the 90's, and Rutgers and Temple were both terrible. The rest of the schools were in competitive lulls other than Virginia Tech, which was rural and didn't have a big following. ESPN didn't want to pay the Big East a market deal in 2005, so it thought it could raid the league and slit its throat, getting the league to take less by raiding 3 schools.
ESPN convinced the BCS to start forcing the Big East out, and then the anti-trust suit hit. There is a 100% the Big East would have been kicked out of the BCS if Connecticut and other states didn't threaten the BCS with an anti-trust lawsuit. That threat kept the Big East as a major conference despite only adding Louisville, Cincinnati, USF, Marquette and Depaul. The Big East crushed it for the next 5+ years in both football and basketball.
Then the next TV contract was on its way in 2012 or so, and rumors were that the Big East was expecting a similar deal to the ACC's for the football schools. So ESPN struck again, raiding the league. Ironically, this raid went very sideways for ESPN, and it ended up wildly overpaying for Pitt, Louisville, Syracuse, WVU and Rutgers compared to what it would have cost to just hold the Big East together. The basketball schools left to a different network, costing ESPN a lot of content and putting a credible competitor in business for weeknights in the winter. UConn, USF and Cincinnati drew the short straws.
The next major raid? When the Pac 12 was coming back to market. The Pac 12 was talking to Apple, so ESPN and Fox raided UCLA and USC, and then picked over the carcass of the Pac 12, once again paying a lot more to raid the league than it would have cost to keep it together. There is not a TV contract coming up for negotiation to trigger a new round of realignment. If anything happens in the near-term, it will be because the conferences are jockeying to impose or defend against a P2 from forming.
22 years ago, ESPN/ABC was the only show on town for college sports. Now there are a lot of players, and fewer conferences. ESPN's constant raids have flipped the dynamic where now ESPN needs to dance if the SEC tells it to dance, because ESPN is in big trouble if it ever loses all that content. CBS/Paramount, NBC/Peacock, Fox, Hulu/ABC/ESPN, Apple, Amazon and Warner/Max all want live content, and ESPN's litany of stupid decisions going back decades have shrunk the market.
While counting on ESPN to be smart is generally a bad idea, ESPN does have an incentive to try to keep the Big 10 or SEC from doing something really stupid that will kill the overall product.