I've never seen an impact cause that type of damage. A carbon fork will usually break before the headtube (usually one of the thicker tubes on a bike of this quality) fails.

In my opinion, a more likely scenario is that this happened way back at the factory, when the cups were pressed in. Either a slightly out of spec tube, or slightly crooked cup can do it. Steel will stretch, but al can't as much, so a crack starts.

Generally, bike companies know the types of failures their products experience. We aren't a Felt dealer, but when I noticed a customer with a Felt had a clear (to me) warranty issue with a malformed right rear dropout, I called Felt, told them up front that this guy was not the original owner, sent them a few pics, and they sent a new frame. This was because they understood the defect was factory-born. Such is the case with this, in all probability. As their rep put it: "this should never have left the factory, no matter who owns it now".

If your bike has been crashed, there would almost certainly be evidence of it on other components, the saddle, the tape, etc.

I think your best bet is to try to have someone at Specialized look at a photo of this. They are technically off the hook since you are not the original owner, but they may decide to help you.

This is one of the many issues that can happen when buying used bikes. Used anythings, for that matter. Sometimes, saving up front is a net loss in the end.