This has never made sense to me because it is essentially arguing that, say, the fifty year period between 1960 and 2010 doesn't exist.

I don't care if maintaining large roads and power and water is expensive. I'm happy to pay for the increased quality of life.

I don't see how this is unsustainable at all. It might need higher taxes or some other way of ensuring that ongoing maintenance actually gets paid for. So what?