It's a cultural thing, but it's not limited to a single program or a single demographic or anything like that. Kids today have a "what can you do for me' attitude as opposed to "what can I do for you". Many of these kids overestimate their own skillsets and falsely believe that they are awarded playing time simply by showing up in practice.
Iowa doesn't get a ton of blue-chip recruits, but it gets plenty of high 3-star recruits that were often times the best player on the field, but maybe due to limited film footage, minimal competition, or lack of size they didn't get the P5 offers they were coveting. Iowa is often times the one and only P5 program that offers these kids, and Iowa has a reputation for taking marginal recruits and putting them in the NFL.
And one thing that works against Iowa is that the starters on both sides of the ball see the vast majority of the snaps. Very often, unless there's an injury, the starters remain on the field from start to finish because Iowa very rarely bludgeons its opponents (and in return, very rarely gets bludgeoned itself). This has to be frustrating for the backups because they're relegated to little more than cheerleaders most of the time.