If Amtrak was subsidized on the same level as the airline or car transportation is, the 7pm departure would arrive at Penn Station around 8am next day. That would actually save you time and money vis a vis the airplane. To be in Manhattan at 8 PM by plane, you would have to leave Chicago the day before and then stay in a hotel at $250+ per night. Or if you left around 7am as most flights do, you would arrive in Manhattan around 11am or 3 hours later than the train.
Trains and planes operate in different yet complementing market niches where each has distinctive advantages. Europeans learned that long time ago, but people who call themselves the government in this country seem incapable of grasping that obvious fact. Or perhaps they are not allowed to by their corporate owners.
Wojtek