Ideally, insurance is wonderful and socialist. Everyone in a risk category pays into a pool, and whoever ends up realizing that risk gets to use the pool funds to set things right or be compensated for loss. It's truly "we all support each other." Protip: everyone is in the same risk pool. It's called "being human".

The problem is for profit insurance. When you put profit motive on insurance, the means change to reach that profitable end. Now it's "charge the highest premiums possible, pay out the fewest claims, underpay on the claims you can't avoid, and exclude anyone who makes 'too many' (read: any) claims". The problem is not insurance; the problem is profit.

I understand "premium" (what you always pay, whether you use it or not)

I think I understand "co-pay" (what you pay at point-of-use (unless you've hit your annual out-of-pocket maximum (unless you're out-of-network)))

I absolutely do not understand "deductible", which seems to mean something different every time I look at it.

And it gets more esoteric from there.

I usually just pay cash-on-the-barrel for healthcare. Most places do a "same day payment" discount that can be up to 40%.

I can explain it very simply. In the US (and I assume worldwide) insurance is an industry that exists to collect premiums and deny claims. The business model is highly successful because if consumers do not wish to participate, the government will assist them by making it mandatory.