To help pay for the inferior product for those who can't (or won't) pay.
ObamaCare: overpaying for the medical attention that won't be there when you need it the most.
What many people don't understand is that those getting a subsidy get different coverage than those who don't, they get a smaller deductible (as low as $0), co-payments (as low as $3), co-insurance (as low as 6%) on top of the subsidy.
That is a damn good product for under $60/month for all ages.