> Try having a pre-existing condition before ACA - no one will insure you because you're too expensive, or your premiums go ridiculously high.

Insurance is paying someone (the insurer) to take ownership of a risk from you (the insured) by compensating you if the risk is realized. If the risk has already been realized then, of course, no insurer will be willing to take ownership of it for less than the cost of the compensation.

The system we have today can hardly be considered "insurance".