I agree; I don't think it's realistic to tell them not to invest at all. The only real way to preserve your money is to invest it somewhere.

I think if the only thing that they could invest in was total-market index funds (or something similar), that would not have too much of a conflict of interest. They'd have the incentive to make the entire market happy, not just individual stocks, which benefits nearly everyone.

If the only stock that politicians owned was VTI or something similar, I think most people would mostly be fine with that. That would still have problem in terms of the uneven weighting, but it would certainly better than what we have right now.