If you're living in the middle of a sea of what you recognize as cultural signifiers, and it slowly dawns on you that those cultural signifiers swarm and bubble around a particular age cohort, I guess the experience of drifting out of that age cohort can be disorientating.
But I don't even agree with what this chap seems to recognize as culture - it's mostly froth, mostly commercial pablum - and it never gripped me much. But I can only guess at this, because he isn't precise enough to define his terms.
The search for meaning in my life came to me in my late teens, and was over by the time I was 25. The meaning I found was not derived from the attention or efforts of other people. I don't expect a decline in marketing of cultural objects towards me, because I've never been much of a target for cultural object marketing that was targeted to the 15-40 age cohort.
I don't watch much TV, I don't watch many movies, I don't go to music events, I don't visit the gym, and I generally feel quite comfortable in life. I don't feel pressure to try and appear young. I've never got much dating advice because I never spent much time dating. The world this chap seems to have been living in (as near as I can tell) is almost unrecognizable to me.
As near as I can tell, the chap has just discovered existential angst. Welcome to late adolesence, is all I can say.