Show HN: In a single HTML file, an app to encourage my children to invest

Original Article ↗ Hacker News Discussion ↗

Concept and Approach

  • App shows each child’s balance and “growth” on a phone mounted to the fridge, aiming to make consequences visible and spark self‑driven curiosity and sibling competition.
  • Parent acts as broker (“Bank of Dad”), applying a fixed interest rate; deposits/withdrawals are currently manual but planned as features.
  • Some liken it to a long‑form “Marshmallow Test” for 7‑ and 10‑year‑olds: exchanging immediate gifts for future gains, but with the option to spend anytime.

Interest Rates and Realism

  • Strong debate around the 15% rate: defenders say an unrealistically high rate keeps kids engaged; critics call it misleading given historical stock returns and volatility.
  • Thread dives into comparisons of equities vs housing, leverage, and local realities (e.g., double‑digit nominal bond yields in Paraguay and similar markets, often offset by inflation and currency risk).

Child Psychology, Values, and Ethics

  • Supporters argue early investing habits can be life‑changing and teach restraint, not gambling; several share positive experiences with custodial accounts and “Bank of Dad” schemes.
  • Critics find it “sad” to swap birthday presents for a number on a screen, worry about kids becoming obsessed with wealth metrics, and argue that meaningful childhood experiences and physical hobbies matter more.
  • Some see the core lesson as “capital beats labor,” sparking ethical concerns about stock markets, growth obsession, and environmental/social impacts.

Financial Literacy vs. Structural Constraints

  • Many agree financial literacy is poorly learned in practice, even where courses exist; others point out big gaps between abstract compound‑interest math and real‑world tools (brokers, funds, taxes).
  • Several stress that knowledge alone is useless without surplus income, highlighting widespread paycheck‑to‑paycheck living and high housing/health costs.

Risk, Volatility, and What’s Being Taught

  • Critics note the app currently depicts guaranteed, smooth 15% growth and omits crashes, taxes, and bankruptcy risk.
  • Multiple suggestions: add volatility, different risk/return “products,” diversification sliders, and even simulated bubbles/crashes so kids experience loss and recovery.

Implementation and “Single HTML” Dispute

  • Some like the lightweight PWA idea; others object that it’s not truly a “single/plain HTML file” because it depends on external React/Tailwind CDNs, which breaks offline use and raises tracking/security concerns.
  • A few bug/UX reports (e.g., date picker crash, missing styles offline) lead to suggestions to inline assets and fix PWA caching.

Alternative Models

  • Numerous variants described: progressive “Bank of Dad” interest brackets, chore‑gamification dashboards, spreadsheet‑based accounts, and heavy emphasis on index funds and retirement plans as kids age.