Have you Read It Yet?!?
The average non-fiction book often sells much less, with some sources stating averages around 250 copies/year or 3,000 lifetime, though a successful book often needs 10,000+ sales for a publisher to consider it a success.
While there are no precise figures solely for the finance/investing genre, general publishing data indicates that selling over 10,000 copies is a significant achievement for any book. Only a small fraction of all published titles reach this sales number.