Keep in mind that a settlement does not necessarily imply guilt, only that a good enough case could be made to set up (in the media, if it would cover it) a lawsuit that could have career ending consequences, regardless of outcome.
In civil suits, as we have seen, a preponderance of evidence is the standard, not 'beyond a reasonable doubt' as it is in a criminal case.
On occasion, money will be paid to make the suit 'go away'. On other occasions (and especially with those who have a chronic problem) the problem is very real.
At any rate, by the time someone is elected to the Congress, they should have a deportment, clarity of behavioural standards, and the political sense to avoid such suits in the first place. At the least this indicates naivete, at the worst, ill behaviour. Frankly, in either case, those who can make fortunes through insider trading should have to pay for such behaviour from their own pockets, and not ours.