Recent studies by Wharton School's Matthew Killingsworth suggest a strong positive link between money and happiness, challenging previous notions that wealth doesn't equate to happiness. His research indicates that the wealthy, including millionaires and billionaires, report significantly higher life satisfaction levels compared to middle-income individuals, with happiness increasing alongside income without plateauing. Killingsworth's findings highlight a substantial happiness disparity between different income brackets, emphasizing that money plays a crucial role in overall well-being, contrary to past beliefs of a happiness plateau at certain income thresholds.