I am willing to make a bet. I will bet that at least 90% and probably 100% of US Senators have money invested in equities. Why? Because, for long term investments, you would be insane not too. Even with substantial drops in the market form time to time, equities outperform bonds and government securities by miles and miles. From this chart, you can see that even if you had the misfortune at age 30 to invest all you savings in stocks the day before the 1929 stock market crash, you STILL would be better off by age 45 having invested in stocks than bonds and your investment would be worth 10 times more at age 65 than if it had been in bonds. And remember, that is the case of investing on the worst possible day of the last century. Any other comparison is even more favorable for stocks. The difference in wealth between stocks and government securities at retirement age is staggering. Any financial adviser who told a person under 50 saving for retirement not to invest some of their money in stocks should be fired on the spot for malpractice.
However, just like Senators who put their kids in private school but oppose school choice for the rest of us, Senators do not think the rest of us are mature or smart enough to invest in stocks. Quoting Senator Specter:
On the issue of privatization, I had some time ago considered an idea to place a relatively small portion of benefits in an investment account, providing that the "security" aspect of Social Security was retained and the investment was under professional management. However, with the severe fluctuations of the stock market, I have since rejected that idea.
Men like John Kerry get most of their wealth from stocks, and would fire any financial adviser who did not invest a good portion of his wealth in equities. He understands that stocks will fluctuate from time to time, but that over decades (which is how one invests for retirement) they are the best choice. How hypocritical is it that he and others are saying "Stocks are great for me, they make me wealthy, but trust me, they're not right for you". More on distrust of individual decision-making here.