What does it mean to have a young master's illness without a young master's life

"Having a young master's disease but not a young master's life" means that although a person was born in an ordinary family, he has a noble disease, which is an excessive pursuit of luxurious and noble life or behavior. They may pursue exquisite diet, high-grade clothes or other enjoyment beyond their financial ability. This kind of mentality and behavior may make them fall into economic difficulties or suffer other adverse consequences.