But that's still on top of premiums. My last year on an ACA "Silver" family plan (2019) was just shy of $20,000 in premiums w/ a $13,500 family deductible.

Health insurance premiums are a tax, not actual insurance premiums priced to one's own health risks.

The Affordable Care Act stipulates various terms which result in young and/or healthy people explicitly subsidizing old and/or unhealthy people:

1) only age, location, and smoking status are able to be taken into account for pricing. And everyone must be offered insurance (i.e. no exclusions for pre existing conditions)

2) age rating factors - premium for costliest person (64 years old) must be at most 3x those of least costly person (21 to 24 years old)

3) out of pocket maximums