Just an observation. My guess is that high cost of "insurance" might be related to the idea that it would be literally impossible to evaluate each individual client what their security practices are, and how risky their behavior is as it applies to security procedures. In other words, pricing of insurance is likely to reflect the wide degree of unknowns as opposed to the absolute risk per se. Insurance is going to have to reflect the riskiest behavior that exists in any of the participants.
My impression is that some of the other brokers have policies of fraud protection, not insurance per se. In other words, it may be that some brokers view fraud losses as a cost of business. But in all probability they couple this with exceptions so that certain risky practices on the part of clients may be excluded.
One thing for sure, unless the client has something to lose, he won't practice security. Kind of like when I rent an apartment to a tenant...if I pay the utilities (heat), the tenant has no incentive to turn the heat down...and therefore the cost of heating goes up. If the tenant pays, he practices a more conservative heating procedure.
I think it would be a good idea to offer a voluntary "insurance" policy and/or fraud protection deal that clients could opt in for a price. That way, those that are worried and/or interested can pay to do it, without the necessity of raising trading costs on everyone.
OldTrader