Those of us who work or dabble in photography are aware of a diabolical disease that affects us - G.A.S., also know as Gear Acquirement Syndrome, also known as leaving your grandkids nothing.
I was a working pro photographer for over fifty years, I used needing to be prepared for any contingency as the reason to maintain an arsenal of lenses and cameras in different formats, not to mention a closet full of lighting gear. I retired from assignment work about 10 years ago, so why am I still buying gear? In part for the same reason, contingencies.
Now many of us, especially of the very old school, believe one or three lenses should be all you need. After all, Henri Cartier-Bresson worked with a Leica with a 50mm lens for many years and became a legend. I recall early on I worked with a Minolta SRT101 and 3 lenses, 35mm, 50mm and 135mm. My shoulders long for those days.