A 48-year-old male reports spending 6-8 hours daily at casinos for the past 3 years. He has lost over $200,000, depleted his savings, and borrowed money from family members who have since cut contact. He has tried to stop multiple times but returns, often "chasing" losses. He feels restless and irritable when he tries to reduce gambling. He lies to his wife about the extent of his gambling. He denies substance use. What is the MOST likely diagnosis?