What most have said above. Three knee surgeries and a bad lower back mean cycling is really the one good activity for me. I love the ability to go out and enjoy nature (sights, sounds and smells) vs. just driving around in a vehicle all the time. As @
Wildwood said, having a large stable doesn't hurt because maintaining them keeps you engaged - especially in the winter when the weather is bad. I ride alone most of the time and enjoy challenging myself to go a little harder, spin the pedals at a little higher rpm or, sometimes, just slow down and enjoy what's around me without worrying about others.
I have the classic car (and it definitely isn't cheap) but the bikes are just more fun.