I have yet to see a transportation system that can pay for itself, stay profitable and still be useful. Measuring real benefits of transportation with current economics seems to be very hard. Almost everything has to be subsidized or accompanied by something that is, otherwise it doesn't work. And you're certainly not going to propose abortion of every transportation, as then you would maybe have less debt, but also no country, so it wouldn't matter anyway. Trains are a real thing that is going to work for 100 years or something, that n billions are mostly some meaningles number flying around... (well, yes, that's only my point of view)