I have a folder of more than 20 dead coins that I mined from back in the Scypt and X11 clone days. Some of those, like the country coins were pumped to hell and back and if you had invested directly in the coin, your investment today is worth zero or peanuts compared to what they traded for,
Ok now I understand, those were not the times to buy. Unless there was a greater fool. Just like ICO's today...
Show me something that went to zero after 8/2015.
I took a break from mining after the crash of 2014 and only started again earlier this year. Clearly in hindsight that was a mistake vs if I had just kept mining. The good news is I held on to most of the coins I mined and for the most part, I'm glad I did. If you are saying that no coin that is being traded now has a chance of going to zero, then I would say that is not a good assumption to make given the fact 95%+ of coins are just clones of other coins with little or no difference to the other coins. In my view, that is another advantage mining has over buying directly. Since your recurring cost is essentially the same for any coin you mine, you don't need to time your purchases and be right.