Part of the fallout from fraud isn't being afraid of losing money. Banks and credit unions are generally on your side when it comes to disputing fraudulent charges. The hassle is getting it all sorted out - verifying identity with sometimes completely inept telephone reps, replacing cards, entering new payment information for recurring charges, etc.
On the other hand, there's also a cost to taking security measures. The time needed to maintain/switch to that separate system has a cost. There's a study[1] on this, but it's done with simple security measures with an unrealistically high probability of getting hacked.
