Bitcoin core stores the data in the same drive as your windows (C:) and I believe it always stored it in the %APPDATA% route. So when you re-install windows and format that same drive you lose all your data including your wallet file.
There was also the fact that bitcoin didn't have a price back then and was purely experimental.

Kind of OT but were they really that bad? Maybe I was lucky because my 20 GB HDD from back in 1990's worked fine and I even still have it somewhere in the house as a relic