Author warns that new traders underestimate bear market severity and are ignoring systemic risks from China's Evergrande crisis, which could trigger global recession given housing represents 33% of Chinese GDP versus 6.2% in US. Market has not priced in contagion risk, and retail option sellers (especially naked puts) are dangerously exposed to potential 50% drops in major stocks over 3-12 months as margin calls accelerate the downward spiral.