Part of it was just wanting an STi, doe. After I test drove one I babbled on about it non-stop to my wife and car friends for 3 months.
Also part of it was having terrible dealer techs diagnosing a simple voltage problem from a prematurely failing battery and having the car leave me stranded 3 times. I had a great relationship with my service advisor so I kept going there after the carefree maintenance period was over and even after the warranty expired, but holy hell were the dealer technicians incompetent. After all of that I wanted nothing to do with that car anymore, but had I just taken it to an independent shop with actual experienced technicians, I wouldn't have had anywhere near the headache.
Our only debts were the house and the RDX we paid off just 3 months later, and leasing a new car was an easy way to get rid of car repair expenses without adding a significant monthly obligation while we were saving for the bathroom project. From a net worth perspective, leasing the STi was really stupid, but at the time it made all the sense in the world for short term cash flow reasons.
eh, oh well.