I heard about it back when I was in high school. Around 2011-2013. I believe I'd also seen some mentions of it online before that but never looked into it. I didn't research it back then as much as I wish I did. I tried mining but didn't have a decent computer at the time, and got bored of it very quickly after mining only around 0.1 BTC. Oh how I wish I could go back in time.
Even I tried a bit of mining in 2014, but wasn't much successful. Then I abandoned my plans to mine BTC and started mining LTC in my office computer. This time I was more lucky, and I was earning around 0.1 LTC per day from mining. And a few weeks later the LTC prices increased to almost $50 per coin and I cashed out most of my mined coins.