Not an Exact Science

Not an Exact Science

From Thoughts On Money [TOM] by Trevor Cummings

May 8, 2026 · 30 min

About this episode

Trevor Cummings and Brett Bonecutter discuss the balance between skill and luck in investing, emphasizing the importance of risk management and diversification.

This week's blogpost - https://bahnsen.co/48QRb50 Trevor Cummings and Brett Bonecutter discuss Trevor’s “Not an Exact Science” blog post, prompted by a prospective client who achieved strong decade-long returns largely because nearly half his portfolio was concentrated in two top-performing stocks, leading to a conversation about diversification and how investors often blur skill and luck. They explore overconfidence, FOMO, and the “exception not the rule” mindset that causes people to discount risk, emphasizing that risk cannot be eliminated and must be respected. Trevor explains Monte Carlo simulations, their usefulness for testing plan viability, and their limitations given unforeseeable life events. They reference Long-Term Capital Management and “When Genius Failed” as a caution about arrogance in modeling. The episode highlights managing mitigatable risks (insurance, emergency funds), avoiding unnecessary concentration, and building flexibility—“the power of the pivot”—through planning, liquidity, and long-term compounding. 00:00 Welcome to TOM 00:26 Client Concentration Shock 02:17 Skill Versus Luck 04:59 Risk Always Exists 06:44 Exception Not Rule 09:00 Monte Carlo…

People in this episode

Host: Trevor Cummings

Guest: Brett Bonecutter

Topics covered

  • diversification
  • risk management
  • investment strategy
  • Monte Carlo simulations
  • overconfidence
  • FOMO
  • long-term compounding

Keywords

  • investment
  • risk
  • diversification
  • Monte Carlo
  • FOMO
  • Long-Term Capital Management
  • portfolio management
  • concentration
  • planning

Mentioned in this episode

Organizations: Long-Term Capital Management, The Bahnsen Group, Thoughts On Money

Books & works: When Genius Failed

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