The question isn't whether they used insider information well, it's whether they used insider information at all.

Using information gained through their political office to inform their personal trading is improper, even if they lose money.

Just because many of these trades are bad or useless in retrospect doesn't mean that didn't try to profit from insider information.

EDIT: And I don't buy the argument that the small size of the trades relative to wealth implies that they're not using insider information. Martha Stewart went to jail over a $230,000 trade [0] at a point when her net worth was likely hundreds of times that amount.

[0] https://en.wikipedia.org/wiki/ImClone_stock_trading_case - interestingly the loss she avoided was only $45,673