American actor Nicolas Cage at the press conference of Mandy during the 51st edition of Festival Internacional de Cinema Fantastic de Catalunya Sitges 2018 in Sitges, Barcelona.

Actor Nicolas Cage was once a top earner in Hollywood, worth around $150 million, but he didn't hold onto the fortune for long. Cage squandered it on a string of expensive and often eccentric purchases, eventually facing foreclosure on several properties. At one point, Cage owned 15 residences across the world, including homes in California and Las Vegas and a deserted island in the Bahamas. He also bought a series of more bizarre items, including a nine-foot-tall burial tomb, an octopus, shrunken pygmy heads, a $150,000 Superman comic and a 70-million-year-old dinosaur skull, which he later had to return to the Mongolian government. What really put Cage in the red financially weren't the eccentric items, however, but his overstuffed real estate portfolio. "What is an octopus, $80? You're not going to go into dire straits buying an octopus," he told the New York Times during a recent interview.

The Neidstein castle near Etzelwang, southern Germany, owned by Hollywood actor Nicolas Cage. He reportedly paid $2.6 million for the pied-a-terre, which dates back to the 16th century. TIMM SCHAMBERGER | DDP | Getty Images

Cage went through a period where all I he was "doing was meditating three times a day and reading books on philosophy" and found himself seeking out the places he had studied and read about. "I started following mythology, and I was finding properties that aligned with that," he says. This "holy grail quest," as Cage calls it, "put me on a search around different areas, mostly in England, but also some places in the States." Throughout the expedition, Cage loaded up on real estate, including two European castles, which he purchased for $10 million and $2.3 million, respectively, and a $15.7 million countryside estate in Newport, Rhode Island. He compares the journey to the process of building a personal library: "You read a book, and in it there's a reference to another book, and then you buy that book, and then you attach the references. For me it was all about where was the grail? Was it here? Was it there?" His final conclusion: "What is the grail but Earth itself?"

What is an octopus, $80? You're not going to go into dire straits buying an octopus. Nicolas Cage

Despite his financial ruin, Cage doesn't regret all of his purchases. "You have good investments and bad investments," he says. "The good investments came from personal interest and my honest enjoyment of the history." That includes "Action Comics No. 1," the first-ever comic to feature Superman, which he picked up for $150,000. For Cage, part of the appeal of real estate also stemmed from his childhood. Growing up outside of Beverly Hills with his professor father, he lived modestly. "I would take the bus to school, and some of the older boys were going to school in Maseratis and Ferraris," he tells the Times. Even at a young age, he longed for more. "My uncle [Francis Ford Coppola] was very generous. I would visit him for summers, and those summers — I wanted to be him," he explains. "I wanted to have the mansions. That was driving me." Like this story? Subscribe to CNBC Make It on YouTube! Don't miss: The Ben & Jerry's founders knew nothing about making ice cream—so they took a $5 class