The 15x15x15 rule, which guides ₹15,000 monthly investment at 15% CAGR for 15 years to build a ₹1-crore corpus, can often derail investors' plans. According to Moneycontrol, Nifty 500 delivered over 15% returns only 10.6% of the time over the past 15 years. Nifty 500 mostly delivered 12-15% returns, which would've reduced the corpus from ₹1 crore to ₹75 lakh.