Years ago (probably starting around 2010 or so), I had the VPS that runs my websites and mail solo-mining in its spare time (not having heard yet of mining pools...or maybe it was before pools existed). This was when you could still have some hope of making money with CPU mining. It didn't cost me anything extra to run as the VPS was already paid for for other purposes.
At some point, it found a block.
Sometime around 2012 or so, those
BTC50 I had solo-CPU-mined got put toward a Radeon HD 7750 and a couple of Butterfly Labs "coffee warmers" (that they ended up having to ship as a cut-down version of one of their bigger miners). I still have all of them...the video card might be worth a few bucks if I cared to sell it, but all of the ASIC mining hardware (BFL or otherwise) I've purchased since are just paperweights at this point. If I'd held onto those
BTC50, they'd be worth the better part of a quarter-million now, instead of the several hundred they were worth at the time.
I'm now giving mining another go, this time with GPUs mining altcoins at exchanges that automatically swap them for Bitcoin. I currently have just one rig with four GeForce GTX 1070s, which should produce $200 or so per month. So far, I've been feeding in outside money for hardware and power and haven't started reinvesting earnings in extra hardware; this should allow my earnings to keep multiplying as the price of Bitcoin continues its trip to the moon.
If the bottom should fall out of the market, at least I have some hope of selling the GPUs off to gamers. (A co-worker's jealous that I have all of these GPUs and use them for mining...he has an older/lesser card that he uses for its intended purpose. I don't do games.)