(Update: A month after this story was published, when people he owed money to asked where the millions were, 50 Cent claimed in a court document he'd never owned any bitcoin. Believe him then, or believe him now?)

A decade ago, 50 Cent was the second-wealthiest rapper in history, pulling in an estimated $32 million a year and living in a Connecticut mansion that had previously been owned by Mike Tyson.

Then came financial troubles, bankruptcy, a comeback--and, it turns out, a brilliant investment strategy.

In fact, an accidentally brilliant investment strategy.

It started with a risky move: taking payment for copies of his 2014 album, Animal Ambition, in bitcoin.

Each bitcoin was worth about $662 at the time, so fans obviously could pick up a copy for a fraction of a coin. Total revenue: about 700 bitcoins.

Let's call that just over $460,000, depending on the exact price at the time. I'm pretty sure he wouldn't know for sure either, because according to multiple news reports, the rapper completely forgot about it.

"Im a keep it real I forgot I did that sh*t," he said on Instagram.

Meantime, as you no doubt know, virtual currencies took off. 

As I write this, a single bitcoin trades at about $11,250. That means 50 Cent's bitcoin haul is worth almost $7.9 million today--a 1,700 percent increase.

It's up almost 11,000 in the past year alone. Maybe you've made some money too.

Personally, I've stayed clear. I wonder sometimes if I'm insane for having done so, watching its value increase like this. 

Of course, it could also make it harder for me to write about things like virtual currency here if I were actively speculating in it.

Plus, I consider myself risk-tolerant, but not that risk-tolerant.

Yet, it turns out that whether intentional or not, 50 Cent's strategy here was a variation of a smart, solid one that many respected investment strategists would recommend.

No, they might not tell you to sink thousands into bitcoin. But once you've made that bet, they might well tell you to move on. Don't necessarily check its value constantly. Avoid the temptation to cash out or cut your losses depending on the day--only to chase something else. 

Let's call it strategic forgetfulness.

In other words, invest for the long term, rather than reacting to short-term price fluctuations. 

Because, despite its meteoritic growth over time, bitcoin and other virtual currencies often have days when they close down. Every investment does. People wonder if they should get out.

All throughout 2016, the future looked kind of bleak, to be honest.

And earlier this month, some people were panicking about whether it was time to sell, when the price dropped back below $10,000.

Heck, I think half my office was debating it.

Of course, it's back up now. Will it keep going? I have no idea. 

But having made a risk-tolerant investment bet, as 50 Cent did, and as long as you're not playing with money you can't afford to lose, the smartest move might often be to just leave it alone.