Just like how the Beatles and Elvis became "classic" after nearly half a century, similarly, there was a time when "Classical Music" was the contemporary "modern music" of its time.
So how were Classical figures like Mozart, Beethoven, Bach et al seen by their contemporaries besides being "famous musicians"? Did they ever had a fanatical following like we have with the most popular rock and pop musicians of today whenever they released a new symphony or "went on tour"?
And finally, were they as politically active as many of the rock stars of our time (like Bono and Bruce Springsteen etc)? Of which I'm only familiar with Beethoven's Eroica and its Napoleon connection.
Bach was known as a remarkable improviser, and skilled performer. He could improvise a fugue on any melody named, which is amazing. Mozart's musical genius was unparalleled, he was famous as a performer in his youth. However in the pre-romantic era,(pre-1800's) classical music was largely limited to the patronage of the church, courts of nobility and the upper class, it did not have a broad based popularity. Performances wee more like background music for the elites while the audience chatted and mingled. However Beethoven was famous as a pianist and a noted conductor in his lifetime.
Many say Paganini was perhaps the first great solo performer of classical music. He is often called the greatest violinist of all time. He raised the technique of the instrument to new heights and also impressed crowds with his tricks of showmanship, for example he would weaken the strings on his violin, so they broke, one by one, but he would continue to play regardless, until eventually managing to play his piece on only one string!
Franz Liszt was a true performing superstar, on piano with him the tradition of concert halls filling with people really came into its own. You could say he was the first rock star of music. He dazzled audiences with his showmanship, incredible technique and musicality. "Lizstomania" swept Europe: Women swooned over him and were driven to a frenzy, trying to get locks of his hair or jostling to touch him. Classical music performances were not the polite, and dignified affairs of today. After playing a particularly impressive phrase Liszt might pause and look at his audience and raise his eyebrows, to underscore it and elicit a reaction. He toured Europe and became a wealthy patron in his own right.