With few exceptions, why would anyone invest in altcoins that can only be traded with Bitcoin? That is to say like Golem can also be traded with Ethereum for example, or litecoin which can be traded with Monero and the USD. It's no secret spikes in Bitcoin are tired almost perfectly inversely proportional to to Altcoins.
Just remeber for markets to work, for everyone who's getting wealthy, there also has to be someone going broke. Right now you wake up to see seemingly ever market is green with a few exceptions of shitty volume altcoins. ZCash, Dash, Ethereum, Bitcoin, and litecoin have all seen insane spikes in price over the last few weeks. I realize there are more people entering the market, but not that money. Something isn't adding up. It wouldn't surprise me to find out whales are also running the exchanges. It also wouldn't surprise me to find out some of the exchanges are completely insolvent, that it is to say, they're trading more in cryptocurrency than there is in money to back it up.
I know most people are like shut up don't talk shit about cryptocurrency. Remember this all still incredibly new and 100% completely unregulated. Most of you probably have cryptocurrency on a wallet just refusing to sell it because you just know the value will increase. Will it, will it really? I truly hope you're right, but it's all still, your entire wealth is just 1 and 0s. The only reason it has any value is because we believe it has value. If anything ever happens to shake our confidence, like an exchange becoming insolvent, the value could decrease to $0 overnight. Be safe, take some profits on the way up and put it towards gold and silver. Avoid trading too much in altcoins.