Over half a dozen residents of this San Francisco 'castle' have become bitcoin millionaires - take a look inside

Melia Robinson/Business Insider

The Crypto Castle is a three-story home in San Francisco where young tech workers eat, sleep, party, and plot the future of money.

A majority of the millennial tenants invest in bitcoin, a new kind of payment system that allows people to buy things and send money with anonymity. There are no banks or middlemen. Transactions are recorded on a digital ledger called a blockchain.

Complimentary Tech Event

Transform talent with learning that works

Capability development is critical for businesses who want to push the envelope of innovation.Discover how business leaders are strategizing around building talent capabilities and empowering employee transformation.Know More

Cryptocurrencies (of which bitcoin is the most popular) have been on a tear in 2017. Bitcoin surged in value from about $200 per token in 2015 to above $4,000 in August. Some believe the digital payment system is headed for a bubble that's destined to pop.

"Over a half-dozen people in the time they've lived in my house have become millionaires as a result of crypto," said Jeremy Gardner, a 25-year-old entrepreneur and investor.

In 2015, Gardner, the then-director of operations at Augur, a market forecasting tool that runs on the blockchain, put down a $20,000 deposit to rent the house. It's become a landing pad for people working in cryptocurrency-related tech.

Here's what it's like to live in the Crypto Castle among newly minted millionaires.

Get the latest Bitcoin price here.