Answer by taking a quote from the following article:

Pink Floyd - The Wall is a 1982 British live-action/animated musical drama film directed by Alan Parker with animated segments by political cartoonist Gerald Scarfe, and is based on the 1979 Pink Floyd album of the same name. The film centers around a confined rocker named Pink, who, after being driven into insanity by the death of his father and many depressive moments during his lifetime, constructs a metaphorical (and sometimes physical) wall to be protected from the world and emotional situations around him. When this coping mechanism backfires he puts himself on trial and sets himself free. The screenplay was written by Pink Floyd vocalist and bassist Roger Waters.

In the mid-1970s, as Pink Floyd gained mainstream fame, Waters began feeling increasingly alienated from their audiences:  Audiences at those vast concerts are there for an excitement which, I think, has to do with the love of success. When a band or a person becomes an idol, it can have to do with the success that that person manifests, not the quality of work he produces. You don't become a fanatic because somebody's work is good, you become a fanatic to be touched vicariously by their glamour and fame. Stars--film stars, rock 'n' roll stars--represent, in myth anyway, the life as we'd all like to live it. They seem at the very centre of life. And that's why audiences still spend large sums of money at concerts where they are a long, long way from the stage, where they are often very uncomfortable, and where the sound is often very bad.  Waters was also dismayed by the "executive approach", which was only about success, not even attempting to get acquainted with the actual persons of whom the band was comprised (addressed in an earlier song from Wish You Were Here, "Have a Cigar"). The concept of the wall, along with the decision to name the lead character "Pink", partly grew out of that approach, combined with the issue of the growing alienation between the band and their fans. This symbolised a new era for rock bands, as Pink Floyd "explored (... ) the hard realities of 'being where we are'", drawing upon existentialists, namely Jean-Paul Sartre.

What else can you tell me that is interesting?
as Pink Floyd gained mainstream fame, Waters began feeling increasingly alienated from their audiences: