Reasons why Mateer would stay:
1) If our collective can get him $200k and he truly believes that he is a future NFL player he may want to stay in a system he knows. Cam Ward is lucky that he fell into a position with a team that has a decent OL, decent defense and a crap schedule. A lot of transfer QB's struggle. One fumble knocked Ward out of the Heisman lead and a loss to Syracuse or in the ACC championship probably kills his chances. Cam is still the poster child for why Mateer should leave though. USA Today did a review of transfer QB's and found that 55% found success and 45% fell short of expectations.
2) He may love Pullman and WSU. Although loyalty is a rare quality these days....it does exist. We don't know how he feels
3) He may not get all that great of an offer in the end. Anyone looking at him objectively and who watched the New Mexico game film knows that he is not a polished QB. He has a lot of great moments, but all BS aside, if he played well in the third quarter, we would have won that game. The defense was the main problem, but that's a track meet we should have won. Another loss and his stock may start to fall.
Realistically, Mateer is gone and there's not much we can do about it. That said, it won't take an amazing QB for us to be 9-3 or 8-4 next year. We have a lot of available wins on the schedule, particularly if our defense quits sucking.
Add to those, that the most amount of improvement in a starting QB is between their Sophmore to Junior year.
Add to those, that if Dickert stays, and can convince most to almost all to stay by truthfully telling them, that next year's team is a National Championship caliber team IF everybody and Mateer stays, and that how would they like to stay and be a part of a National Championship caliber team. WSU almost went 12-0, 11-1, almost had a CFP year this season. Next season if everybody, including Dickert stays that can stay, including getting transfer portal upgrades to help fill a few holes, and upgrade, then almost every position will be redshirt juniors, redshirt Seniors, returning starters that will have probably developed, progressed, become better, become even better, will be comparable to 1997, 2002, 2018, etc, talent, starting wise, and would have a even better chance then this season of both making the CFP, winning 1,2 CFP games, ABSOLUTELY DOMINATING a semi weaker schedule, etc. That's not a guarantee, but there would be a much better chance. A good enough chance, that Dickert can sell players on that chance, and the higher at risk players of leaving like Mateer can get 333k, NIL deals, Truck, etc, which could be enough to get Mateer and other at risk players of staying. Mateer could also make a serious run at Heisman, NFL, at WSU, next coming season, if he stays at WSU, that he might not do at a Blue blood. Remember Florida, FSU, LSU, even Alabama could finish at 9-3, and 9-4 by end of season, etc, so going to a blue blood is no absolute guarantee.
Add all that to the other reasons Flat named , and Mateer could very well stay at WSU.