That attitude of “I worked really hard and it didn’t matter” can follow them. Yes, there are disappointments that we have to deal with, but these are still kids, and the build up to college has gotten so out of hand the last decade…kids feel like their worth is measured by their acceptances. It’s not like someone kicked over their blocks or they lost a ball game, someone kicked 4 years (25%) of their life over with disregard (in their mind). The high level 4.5s that are denied - seem to fall the furthest. Not trying to be dramatic, and my kids will tell you they have heard “deal with it” many times, but this can be a blow to their confidence that they carry with them for a long time and into college, making for a rough start there.
So maybe for OP it isn’t a big deal and he will likely move on to his other great acceptances, but for some it casts a long shadow to be sensitive to. Just get excited about the one they do choose and that chooses them! Plan something fun now to do in summer that isn’t about shopping for dorm bedding, something unrelated to college while you still have them. Distract them so they move on.