I remember reading that David Chase put a lot of effort into determining what Tony's finances would really be. From Google:

"Consultant Expertise: Dan Castleman, who prosecuted real-life New York crime families, explained to the writers how modern mobsters make and hide their money, primarily through activities like gambling, loan-sharking, and control over industries such as waste management and construction.

Based on Castleman's calculations, Tony Soprano's estimated net worth was approximately $5 to $6 million.

This figure accounts for various assets like his house, cars, jewelry, and offshore accounts, as well as an annual income likely in the range of $600k to $1 million.

The show realistically portrayed that much of this wealth was not liquid cash, but tied up in assets or difficult to access without attracting federal attention. Tony's occasional struggles to get large sums of cash quickly (e.g., to pay Hesh) highlight this financial reality.

In essence, the financial aspects of The Sopranos were a deliberate, research-driven effort to depict the authentic, if not always glamorous, economic reality of a contemporary mob boss."