That’s tough. I would think that it fluctuates. THEY ARE ALL GROSSLY FILTHY RICH. 

The most rich? Probably Marius, or Armand. But this is the gif I have that’s on topic so this is what you get.

Marius has been around for a LONG time, whatever money he got in the beginning of his vampiring has accrued to an enormous amount over all this time. I don’t think it’s just based on selling paintings, which I would think he does more for fun than financial gain, but could be both.

(I like to think Marius also givens painting lessons as a hobby bc he does love to teach!)

In no particular order:

Lestat’s money was there before he was a rockstar, he had to have alot of startup money. He talks about hiring the best people and buying the best equipment for all aspects of getting the band updated and concert ready. He talks about hiring security and lawyers. He had that money already, it was waiting in bank accounts he had set up in the 18th century. Remember, he started off vampiring with a big treasure chest of stolen money and jewelry from Magnus’ victims, which he invested.

Louis is rich bc he was a plantation owner and owned property in NOLA. He was careful with banking and originally thought Lestat chose him for his money. AS IF! Louis is also a great gambler, he has a knack for cards, and can win huge sums to invest. Louis also loves books, and probably is in the vintage book business. Louis also probably gets money from Lestat, if he needs it. 

Armand initially arranged for dives for treasure from sunken ships, an archaeological find, “a cheap piece of South American property yielded a long forgotten emerald mine.” And that money was invested. He owns and runs the Night Island, and other businesses, which are a constant source of incoming profit.

Daniel had money from the publishing of IWTV, and later other books, but his money really comes from Armand.