Perna,
Your math only works if an individual is not seeing a doctor or pdoc for anything else. If the person is on medication, or has chronic illness, or needs to see their Pdoc monthly these cost go into the deductible and then are cheaper with the insurance depending on what the person needs in regards to their other health care. Needing to see specialists for other conditions also has to be taken into account. When I had student insurance (that honestly isn't that expensive, and had limits) the benefit of not having to pay $300/ mo for a medication until I hit the benefit cap (don't get me started on this). So there are times where insurance is cheaper.