Most places offering 401ks also offer several different mutual funds in which people can invest their 401K funds and are able to diversify within those — the companies can’t provide everyone with a different set of investment options. If you are already over 59 1/2 or left the company, THEN you can usually roll over your 401K into a Rollover IRA, where you can invest it as you choose, at a brokerage firm or mutual fund family of your choice.
Mentioning Enron is ridiculous — people who were stupid enough to have all their retirement savings in one stock — Enron, indeed lost all their money — but people who had their 401k investment in different mutual funds offered by the company through a fiduciary, were not impacted.
All financial advisors always tell everyone to diversify.
good post