People today may remember John Denver only vaguely, either for that wedding staple, "Annie's Song" or that standby of the karaoke bar, "Take Me Home, Country Roads". His stab at going into space during the 80's was belittled in many a comedian's monologue and until his untimely death in an experimental plane in 1997 he had been largely forgotten. In the 1970s, Denver was easily as big as Michael Jackson, with sales exceeding 100 million albums.
In the '70s, Denver was everywhere. High on the charts, on t-shirts & paraphernalia. He was one of the first pop stars to really exploit television, his tv specials were watched in the millions and his 'look' of the dutch boy haircut, granny glasses and western shirts were copied by his many fans. He appeared on Newsweek and Time. Rolling Stone had to grovel to his manager, Jerry Weintraub, for an interview and to put him on the cover.
Many an acoustic musician admitted they were inspired to pick up a guitar during Denver's glory days. Alas, the punk & new wave era saw Denver disappear off the chart but for many a baby boomer or Gen Xer, he holds a soft spot in our hearts.
Hated by the critics during his peak years, Denver has undergone something of a critical reappraissal since his death in 1997. Tribute albums abound, and Denver clips get high views on youtube. Eaglerock released a dvd of live performances last year, which sold well, so I suspect that all those Denver fans didn't go away, they were just waiting for the right time to admit it.