Lance Armstrong was in a dark place after his lifetime ban for doping - and the financial hardship that came with it certainly didn't help.

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The American faced lawsuits seeking tens of millions of dollars worth in damages after his dishonourable life as a doping cheat surfaced, leaving him in a world of trouble.

But the 47-year-old has survived, revealing in his first television interview since 2013 that an investment into a venture capital firm in 2009 has led to an astounding windfall.

Armstrong invested US$100,000 (NZ$145,0000) into an app that was valued at just $US3.7 million at the time but today it's worth over $US120 billion.

The app? A ride-sharing service many know called Uber.

Armstrong wouldn't say how much his share in the company was worth now but admitted it "saved our family".

Instead, he told CNBC how he got into the company thanks to a phone call by former Google employee turned billionaire investor Chris Sacca.

"He was starting his own venture capital fund, Lowercase Capital, and he called me saying 'I'm looking for investors, would you invest?’," Armstrong said.

"I’m thinking to myself, this guy has a huge personality but he’s also very smart and very well connected. So I invested in Chris Sacca. I didn’t even know that he did Uber. I thought he was buying up a bunch of Twitter shares from employees or former employees, and the biggest investment in (the) Lowercase fund one was Uber."

Armstrong reached a $US5 million settlement with the US federal government in April due to his doping past but they could have sought up to $US100 million. It wouldn't have mattered.

"I didn't think I got off scot-free because the settlement for $5 million was probably the 10th settlement ... once you total up all of it — loss of guaranteed income, legal fees and settlements — it came to $111 million," he said.

"So I don’t feel like I got off easy."

The $100,000 share he bought in Uber when it was worth $3.7 million in 2009 would now would be worth US$3.24 billion ($NZ4.71 billion) today - a 3,243,143 per cent increase in value over nine years.

Armstrong was handed a lifetime ban from sport in 2012 for his fraudulent use of performance-enhancing drugs throughout his cycling career.