Speidi, who shot to fame in The Hills in the noughties, told The Mirror that fame and fortune had gone to their heads - and they had also become convinced that the world was going to end.
Spencer said: "We made and spent at least $10m. We heard the planet was going to end in 2012. We thought, 'we have got to spend the money before the asteroid hits'.
"Heidi came from a poor background, she couldn't afford to buy noodles. To go from that to super-rich millionaire in your early twenties is hard to deal with. And I just lost the plot. I would give friends £15,000 cash for their birthdays, I would buy people cars. When you start buying people cars and you're not David Beckham you're heading for trouble."
And Heidi admitted to developing a designer handbag habit, in a bid to "keep up" with her idol Victoria Beckham.
"I grew an obsession with Birkin handbags. They were like £13,000 each. I had wardrobes full. But we wanted to keep up with the Beckhams. I love Victoria's style."
She admitted that she'd been a Posh fan as a child: "I was obsessed with the Spice Girls. It was the first concert I ever went to. I loved Posh so much. We absolutely love them."
And Spencer added: "The Beckhams have been our idols since he was scoring goals for England. We love being the new Posh and Becks."
They even went so far as to hire the Beckhams' former bodyguard to protect them.
Spencer told OK! magazine: "We actually hired Victoria's bodyguard. We tracked him down - this guy got to be with the Beckhams. We needed his energy in our lives! We had their bodyguard for six years."