Before 2014 plans were required to cover pre-existing conditions as long as you had “prior credible coverage” and didn’t have a lapse in coverage for more than

Before 2014 plans were required to cover pre-existing conditions as long as you had “prior credible coverage” and didn’t have a lapse in coverage for more than a short period of time. If you let coverage lapse, plans were allowed to impose a waiting period before coverage for the existing condition would start. Since 2014, the “fix” is that now it’s just required to always have insurance, or else you pay a penalty. Then for the last couple years the penalty was repealed but the coverage for pre-existing conditions is still guaranteed, which does open up a hazard that people will only buy insurance after they get sick... but really the risk of a sudden health issue is still high enough that most healthy people will still want coverage.