Hi Bryan,
unfortunately consumer debt has raised in the past few year (after 2000). This was the time where interest rates really dropped dramatically (in view of Greece joining the eurozone in 2002). Money became cheap, a new type of loan occurred (called consumer loans) for buying cars, furniture, and generally chance was given to the public to borrow cheap and buy goods. People went ahead and borrowed like crazy building up their debts. Low mortgage interest rates also pushed house prices up.
I would take your point with regards to people owning a lot of equity in their homes. The culture in Greece is somewhat different to the English one when it comes to house ownership. It is typical for a lot of people to build their houses on their own and hence own their houses outright. Also there is a lot of support from the family to kickstart a young person on their move on the property ladder either by parents gifting estate to offspring. So it is average for people to own their houses. However, given the fact that a lot of people move to other places for work or studies the house renting market is also active and dynamic.
You are spot on regarding central Athens. I would generalise this to other towns such as Patras (north Peloponese) and Thesaloniki (or Salonika) in the Macedonia region of Northern Greece where there are a lo tof students. Regarding Athens you will need to be careful as to who you rent your place in the centre of town as more areas there in recent years have been dominated mainly by migrants from other countries. Don't misunderstand me, there is nothing wrong with this, it is just that you need to be more thorough in your checking of potential tenants.
Let me know Bryan if I can be of more help.
ARIS