"…borrowed from extant WoD materials…"
There ya go. See, in most fantasy milieux the economy is on the Silver Piece standard, however characters are routinely generated using GP. So if you multiply the numbers given by 20 it becomes credible in terms of purchasing power.
Now, the "homebody" kind of noble will spend much of his disposable income on living up to the next level of lifestyle expenses. He might only have 1000 Quid left over, but that's his choice rather than necessity of his social station.
The adventurer has other ideas for disposable income which the majority of his peers find quirky. They don't mind because that gives them more room to maneuver behind his back.
What it still fails to take into account is capitalization. Essentially no fantasy milieux have stock markets, limited liability corporations, money markets, futures, and so on.
In pre-capitalization era retail mark-ups for many trades were 5%. Labor was cheap. Even well into the 19th century merchants routinely operated on mark-ups as low as 10%. Fluidity of capital and trade goods brought by cheap communication and transportation began to change that.
In a post-inductrial society Nike sells shoes to distributors for four times the cost of manufature, and the distributor to retailer for double his cost, and the retailer to the consumer for double again. Labor is expensive and bulk transportation ridiculously cheap.
Fief-holder of a major city could well be generating personal income of lifestyle + 20,000 Silver/mo in, say 18th century Britain. In the industrial revolution he has invested in numerous real estate projects and shipping concerns centered on the fiefdom, and generates double the disposable cash.
(He can't really rape the system like a rail baron, noblesse oblige and all. Otherwise he'd be raking in 10 times as much.)
In a Traveller setting the nobles are a bit harder to figure, being a mixture of old blood and new blood; old money, old new money, and new new money. In fact many are honorary titles bestowed upon political appointees from the stratosphere of the business world.
A fiefholder of any note would sit on corporate boards, hold small chunks of every big fish in his local pond, and have a thumb in every real estate pie around. Much of his lifestyle is "perked" and the dividends alone could generate Cr250k per month, easily.
If I'm the Grand Earl of Los Angeles and I'm not getting that much it's because the whole economy has tanked. Heads are gonna roll when I find out who dropped the ball while I was in Monaco attending Imperial social functions for the required face time in the Prince's courts!
(right click | save)
Trump owns a handfull of major buildings and businesses and I bet he's got walking-around money on the order of Cr1000 a day (very conservative on conversion from 21st cen money). I have known folks—typical business owners—who felt naked without a thousand bucks in the wallet, and might spend that in a week. What would that be, maybe Cr1000 a month?
