Advantages to keeping old road bike after getting a new one? (medium-length)

I regretted selling an old bike years ago after I bought a new one. The new bike was too precious for city breakfast rides. If I stopped with the bike club to go into a trendy Manayunk restaurant for breakfast, the new bike might attract a lurking bike thief, who has been watching with his ever-ready bolt and cable cutters for such an opportunity.

So use the new bike for rides in the open country and keep the old bike for urban adventures.

The time to sell comes when you must upgrade your living quarters to make room for another bike. Then sell the bike that stays under wraps in the basement or the garage that you may ride just once or twice a year.