Let's start with a theory - a conspiracy theory.
Real Estate as an asset class is heavily invested in globally. Many investors don't see the property they invest in. Pension schemes for example - the individual just understands their cash is invested in various portfolios. The agents decision to invest is performance led - yield driven. The agent may not necessarily know much about the portfolio either... All in good faith.
What if it was all Ponzi Scheme to begin with. With only a few real valuable buildings existed; a few ruins thrown in; and a few make believe buildings (with false property deeds) making up the entire investment portfolio.
High yield property portfolios, seen as relatively safe investment can attract large flows of capital investment enabling a increase in yearly yield pay out using incoming monies. The cash flow would enable the illusion to keep going... If one illusion so existed.
What happens when the tide goes out. Crisis.
Well firstly incoming investment drys up; outgoing payments need to be maintained - to maintain the illusion. But soon the reserves run dry and people responsible evaporate into thin air.
All the above is just a conspiracy theory. But imagine too you added NAMA into the mix as a holding institution for such fantasy and defunct portfolios; now that would be a real whopper of a theory. Beyond public/private scrutiny... Data classified. Statute of Limitations 12 years. Life cycle of Name 2008 to 2020. Twelve years exactly. It would all make a great story.