Why Multiple Road Bikes?

I’ve been riding about eight years and average approximately 4,000+ miles/year. I have never owned more than one bike at a time because I buy a bike that meets my needs that I also enjoy.

Just curious, why do so many cyclists own multiple (3-4-5) bikes?

Update: Some really great and funny responses. However, my question is strictly regarding single-purpose Road Bikes. I understand if you have Road, Gravel, MTB, Track, Tri, etc.