Unless you've been living under a rock for the past few months, you will have noticed the internet's new obsession with investing in a cryptocurrency called bitcoin. The reason why is obvious when you look at 50 Cent as an example - he's just been made a millionaire out of it.

50 Cent at the 'Den of Thieves' premiere50 Cent at the 'Den of Thieves' premiere

The 42-year-old rapper dropped his last album 'Animal Ambition' back in 2014, and while he only sold 124,000 copies within the year of release, that album has now brought in between $7 million and $8.5 million because he decided to accept a then little known currency called bitcoins for the record.

Each album was sold for a fraction of a bitcoin, and resulted in the accumulation of 700 bitcoins. He happened to completely forget about it all, which is just as well because the value has skyrocketed over the last three and a half years.

If he'd have got round to selling his bitcoins in 2014, he would have only made around $400k given that they were worth only $662 back then. That being said, if he'd have sold them all when the value peaked at $20,000 per bitcoin back in December, he would have made a cool $14 million.

Still, $8.5 million is certainly not to be sniffed at and 50 Cent is enjoying gloating about his smart business move on social media. 

'A little bitcoin anyone? LOL. I know I make you sick but excuse me I'm getting to the bag', he wrote on Instagram. 'Not bad for a kid from South Side, I'm so proud of me.'

More: 50 Cent talks 'Den of Thieves' with Gerard Butler

It's quite an impressive thing to happen to the star, who only three years ago filed for bankruptcy. But he's invested in all kinds of business ventures in the past, one of his most fruitful being Vitamin Water which was later sold to Coca-Cola, bringing in a $100 million cheque for 50 Cent.