I sold a _very_ small IT company in 1998 for $50K when I got a "real job"; the truth is, I didn't earn much on my own company, and it was doomed to fail anyway. I was only 22 years old, and my financially over-protective dad (thanks, though, and RIP) insisted on putting all the money into pretty secure stock funds.
I've never needed the money, and after my dad passed away in 2012, my brother's lawyer and accounting company keeps it under control. Based on a fairly conservative avg. interest of 7% since then, I should be good for $190K now, increasing approx. $1K+/month at the moment. If my rather poor math skills serve me right.
The reason I don't bother about this investment is that I'm currently OK with the "normal pay", but it's also because I'm afraid of being disappointed if I look into it, or (worse) get so excited I spend it all on crap. :/ Also, if I never bother about those money, I guess I'll never miss them when the stock market _really_ crashes. :)
As of today for 2017: 14.24%
Dec. 31, 2016 11.96%
Dec. 31, 2015 1.38%
Dec. 31, 2014 13.69%
Dec. 31, 2013 32.39%
Dec. 31, 2012 16.00%