See this is the opposite of what I've noticed. Yes, bitcoins and litecoins are sound investments because they're basically gold and silver, but most of these other altcoins can be traded for either of them, and my hashrate gains me a lot more net profit by mining these altcoins and trading them for bitcoin or litecoin immediately. So while the altcoins might be considered riskier, it's also a better investment to mine them outright and trade them for the more well-known coins. That's just my perspective, anyways.