Has anyone paid out of pocket for medical care that was actually cheaper without insurance?

[FBaggins]

4. Yes - a bunch of times

Answering in the context of a specific medical service - this can be particularly likely if you have a substantial annual deductible that you don't think you'll hit by year-end.

Note that optometry is very often a separate policy from health insurance. It's not at all uncommon for the premiums for that policy to exceed what you actually get out of the coverage.

Indeed, this should be the norm for most insurance (medical/auto/etc.). Insurance companies wouldn't stay in business if the average person received more in payouts than what they paid in premiums. But insurance isn't really there to reduce costs for everyday services. It's there to protect against the big expenses that are unexpected.