Genuine questions, is it cheaper to travel to Europe than to travel within the US?

So I'm planning a trip to the Westcoast, it'll be a 11 day roadtrip and have most things booked, looking at around 2.5k per person (me and my gf). This includes flights, car rentals, lodging for 10 days, and estimates for food+gas+activities.

Now I'm wondering, would taking a trip to Europe be cheaper than this? I've seen people saying so but it's hard to believe, maybe international travel is cheaper than I thought?

Author: Lord_Snow179