I'm not sure how my simple quote of a fact, with no commentary whatsoever, leads you to believe I "don't mind that your broker loses your 100k (of 500k+)" I am generally against hyperbole and intellectual dishonesty and correct it when I see it. If letting everyone know what the real final outcome at MF Global was bothers you so much you shouldn't have posted it as the only example of a failing FCM that was needed! FCMs fail, PFG Best is actually a better example. So do banks, dozens upon dozens have failed during the same period that these two FCMs failed (that's real dozens, not made up dozens https://www.fdic.gov/bank/individual/failed/banklist.html). One must assess the risk of it happening and the impact of that on you. Compared to the trillions that have passed through FCM's hands during the period that MF Global and PFG Best failed, you're much more likely to be killed by lightning than suffer a significant loss at the hands of your FCM and certainly more likely to have your bank fail. Not to say you shouldn't take action to protect your funds at an FCM (or a bank, or to ensure you aren't struck by lightening), but let's not get carried away with the hyperbole.
Certainly is the probability of losing money by a failure of an FCM a many fold multiple of the probability of being struck by lightening. You are excused though, they don't teach even simple stats in MBA programs.