Even if you avoid the issue of the auto dealer wanting to limit the abuse of their policy, you have to realize that the discount they give is 25% off of some stated price. It might be 25% off the sticker. They don't want to lose money, the 25% represents the haggling they avoid by selling to the employee. This means the discount might not be as large as you imagine, because you wouldn't have paid sticker if you had purchased the vehicle on your own.
The other issue you will have to deal with is taxes and registration. When your friend drives the car off the lot, the car will have to be registered with the state. Then they will have to sell the car to you, and that transaction will have to be done though the state, for a price. Then you will sell it to somebody else. These transaction fees will cut into your profits.
It is likely that when the potential purchaser runs a VIN check through a service it will show multiple owners, which can cut the estimated resale value.
The manufacturer will also have to be notified so that all the relevant warranty coverage is still intact.
The question is for that final sale: can you offer enough discount compared to the new car dealer? and still make enough profit to be worth the hassle?