Apartment complexes were built at boom town construction cost to rent out for more than a Malibu beach house. (studio apartments were between 1800 and 2000 a month, 2 bedroom for 2400 to 3600, and anything larger went for more. Houses were at a premium, renting 5000 a month or more.)
Expecting either to make a killing or that the boom would last forever, the investors overbuilt.
Those of us who had been through an oil boom before knew it wasn't going to last and just shook our heads.
The rent still hasn't come down much, but the occupancy is down considerably as those who lose a primary job in the oil patch are moving back where they came from and taking family and savings with them.
In the end, without a resurgence in oil prices, a reduction in rent (refinancing or change of ownership), those properties will likely lose money. Most do not have handicapped accessibility (think 4th floor walk-up, no elevator), so they won't be converted to 'senior citizen housing' in the future.
That may well be part of what is coming back to the banks now.
For the rest, look at the likes of Silverado Savings and Loan when the last oil boom died (1986). Equipment bought at premium prices will eventually be auctioned off for pennies on the dollar.
You just wrote the story of every boom, oil and otherwise, since the dawn of time. Today, we get to visit lots of those places and call them "ghost towns" while discussing the stories of painted ladies, raucous living, and getting rich quick only to get poor quicker. We have plenty of these places here in Oklahoma that date back to the 1920s. Some even lasted into today but most are showing the strain from the multiple cycles of the boom-to-bust oil field.