Not really surprised.... we all know these cars built like rocks. I kept my '06 for 10 years and almost 400K km, and ultimately let it go when the engine failed and was looking at a big bill to replace. Motivation to change cars was enhanced by the fact I can write it off for work as well. Otherwise, could have dropped a new (used) engine in and probably got another 3 years out of it...
In our case: Gen-1 bought used in Oct 2005 with 49k miles - 'sold' to house keeper in April 2016 with 173k miles. She needed reliable transportation and we needed her service for my wife. Gen-3 bought new in May 2009 with ~4 miles - sold in January 2017 with 73k miles with some aftermarket enhancements and 'lessons learned' maintenance from the Gen-1 Gen-4.5 Prius Prime bought Dec 28, 2016 with 4 miles - future modification, casket handles and a some sort of weird Viking funeral arrangement perhaps at Burning Man. Or perhaps, 'an experiment gone wrong' Bob Wilson