It was specifically sold as 'insurance' to the public around the time it was being passed.

Well except for a short period where that was going to be deliberated on by the courts, where they stopped calling it insurance since SCOTUS indicated this insurance wouldn't be constitutional, so instead they put it under general welfare clause but then changed up their rhetoric immediately after it was found constitutional back to it being insurance again.

Also the people that wrote the bill later admitted they intentionally wrote it in a confusing as way to evade public and judicial scrutiny.