I have a primary road bike (Lynskey), two backup road bikes (Bianchi or Cannondale, depending on which coast), and a commuter bike that is mostly a flat bar gravel bike (road rear tire and cassette, easy enough to swap out if I wanted to turn it into a gravel rig).
It took 14 years to acquire my second bike, and only four years to acquire the next two.
Given where I am for the next year (Northern CA), I’d love to give gravel a serious shake at some point, or even dip my toe back into XC - haven’t done any MTBing since high school. But I don’t think my wife wants any more bikes in the garage…