The biggest reason why your 401K is garbage is that the majority of 104k's are managed by fidelity. NEVER PUT ALL OF YOUR EGGS IN ONE BASKET. When you do, organization in charge will almost always mismanage those funds to the point that it becomes a ponzi scheme. In other words, in a real financial crisis, they are very unlikely to be able to honor all of the requests to close out those accounts. And if they could, the government would STOP THEM to prevent the market from crashing.
Diversification is key. 401k's are consolidate, not diversify!