Confused about health insurance—need advice

My family and I have been on state insurance for the last few years (soo much simpler). I just finished grad school, moved to a different state (FL) and got a new job that doesn’t offer health insurance. As a family of 5, the market place premium was around $1800 for a decent plan (recommended by my accountant) $7500 individual deductible and 10K family.

My boss, who is pretty frugal and seems financially savvy advised that I would be getting a very rotten deal by signing up to a good health insurance plan this late in the year (barring any major emergency). His reasoning is that I would have to pay the premium for the remaining months, and also pay all medical costs out of pocket until the deductible is met before realizing any benefit from the plan.

One of my kids needs monitoring by ophthalmology for accommodative esotropia (lazy eye) and all three need test done with by GI. Neither condition is life threatening nor require extensive care—just exams and the occasional prescription.

We also recently found out that my wife is pregnant but won’t be due till next year.

Based on my boss’ rational, I would have to pay the premium ~7200 AND pay the deductible assuming 10k family— total 17,000 out of pocket before I realize any benefit from the insurance company. His argument is that it would be a better financial decision to pay out of pocket for these expenses (specialist visits, exams and bloodwork) and then start the new plan next year.

I am considering opening an HSA account and signing up with an HDHPs (high deductible health plan) just in case of catastrophic emergencies.

I am extremely confused about the deductible situation and health insurance as a whole. It actually doesn’t make sense on paper to me and doesn’t seem fair to pay a premium this high this late in the year just to end up paying out of pocket anyway because of not reaching the deductible.

What a reality check lol. Is this actually how it works? Is it true that insurance doesn’t pay anything until your medical costs have reached the deductible? Any recommendations?

Edit: Ages: 31M 28F 9M 6F 4M