Why is classical music so highly regarded?

I wonder why classical music is so highly regarded? Most of it is just monotonous. Presumably it's the best music from bygone times, so we need to compare it to the best pop music. The emotions, feelings etc elicited by certain pop music are greater for me than any classical music eg "dark side of the moon" by Pink Floyd, "mother suite" from atom heart mother by Pink Floyd, "I'm not in love" by 10cc. "If I fell" by the Beatles, "Closing" by Philip Glass etc.