As a concept, "if" may be mere conjecture in real life. In fact, though, if Stuart Sutcliffe hadn't taken his best friend John Lennon's advice back in 1960 and left art school to play bass guitar in his band, the music world would now be quite different.
That's because Sutcliffe joining Lennon, fellow guitarists Paul McCartney and George Harrison, and drummer Pete Best, allowed his Liverpool group — the Beatles — to take up an offer of work playing seedy clubs in Hamburg, West Germany ... and the rest, as they say, is history.