Most of Elvis' career missteps (and indeed there were many) were orchestrated by Parker, who was really only using Elvis to make HIMSELF rich! Elvis wasted away, and Parker didn't do anything to stop it? Granted, Elvis was high-strung, and wouldn't listen to anyone around him, but Parker probably believed that Elvis was worth more to him dead than alive. And unfortunately, he was probably right.Considering how well Lennon came across in the Beatles' movies, and in "How I Won the War", Elvis could have asked Lennon, "When are you going to stop banging away on your guitar and become a movie star?" In the 1960's, Elvis (and more importantly, Tom Parker) were looking at some pretty powerful role models. Bing Crosby, Frank Sinatra, Dean Martin, Sammy Davis, Jr. were, or had recently been, shifting between selling records, playing nightclubs, and making movies. Selling rock and roll records to teenagers in the late 1950's wasn't seen as being the ticket to a long-term career. So, when Elvis came back from his stint in the Army after being drafted, and had to make a comeback, it made a lot of sense to forget about trying to impress a new crowd of teenagers and instead reach out to his earlier fans, now grown older, by making movies. And, as time passed, it made sense for him to continue to reach out the that same further aging audience by shifting to Las Vegas stage shows instead of trying to sell records. If it wasn't for his self-destructive habits that caused his early death, Elvis (and Tom Parker) had a great career, re-inventing himself periodically to avoid being left behind as trends and tastes changed.
Meanwhile, Eddy Arnold FIRED Parker, had a long career, and lived well into his '90s.
And then we went too far in the other direction in the '70s, with the creation of the "disco" chart. Apparently, someone out there thought that disco had longevity. I would guess that that disco chart, and the grammy for best disco recording, lasted about five years at most. (If only RAP had had such a short shelf life!)Remember, the concept of a recording act maintaining any sort of real longevity selling recordings is relatively recent. When artists we were starting to get a little older in the 60's looked back at the artists who came before them, no one who started a career out of recording hit singles survived long just selling hit singles. Those whose careers lasted any length of time diversified into alternate media. The concept of making a career out of selling recordings, and touring to support the sales, was unknown in the 60's, except for bandleaders. It wasn't until some of the solo artists or rock bands of the 60's continued to have some success in later decades that anyone knew it could be done.