Opportunity cost

I was saying that I would sell my car, and people began asking about the price. I didn't know what I wanted for it.

It's a 2004 Toyota Corolla LE with 139,000 miles. I bought it from a dealer in 2009 for $7,821 (with 99,000 miles) and assumed that its value would have dropped considerably in two years. I searched kbb.com for its private party value (in good condition):

$6,325!

It's amazing to me that this opportunity cost of car ownership has elluded my attention until now. I have had thousands of dollars of capital at my disposal. Why have I hung on to it for so long?

I'll save my hypotheses for now. I only wanted to point out that it's easy to take car ownership for granted. It's also easier to let go of a car when realizing a significant financial boost.