Well, if you have $15k in the bank, or can borrow it in a pinch, you'll spend much less in the long run.What good is coverage, if the deductible is $15,000???
This is actually how insurance is supposed to work. It isn't something you're supposed "use", it's not a tool to "finance" routine health care (not a good tool anyway). Insurance is a backstop if everything goes to shit. The most prudent way to be insured is to have the largest deductible you can manage, which should be accompanied by very low premiums aka "catastrophic policies".
The biggest crime of ACA is that it did away with these kinds of policies. You can still get nominal "catastrophic" policies with high deductibles, but the low premiums have vanished because of the additional requirements to cover pre-existing conditions and regular health care expenses (checkups, prescriptions, etc ...).