That changes nothing. The aggregate probability should be the same. Even if we assume that the insurance company will modify premiums based on the type of work the company does, they'd do that to the individual as well, as they ask your occupation. The chance that the insurance company could get scammed by a covered person lying to indirectly through their employer is is the same as the insurance company getting scammed by a covered person lying directly to the insurance company.
Regardless, this is all covered under pre-existing condition clauses and contract law: i.e. they most definitely WON'T be out the $200k from your hypothetical.
The aggregate probability of a heathy 25 year old deciding to pay full market price for Heath insurance is lower than a sick 25 year old. However, you also get people who discover there at an increased risk for a disease and decide to get coverage etc.
PS: Heath insurance company's are vary rational, if the risks where equivalent they would charge close to the same rates due to market forces. Instead identical group plans even for small groups can be significantly cheaper.
Regardless, this is all covered under pre-existing condition clauses and contract law: i.e. they most definitely WON'T be out the $200k from your hypothetical.