How an ex-rocket scientist invests to live off his portfolio

Executive overview

Most retail investors are told to build a 60/40 stocks-bonds portfolio. Alex — an electrical engineer turned full-time investor — argues that bonds are unnecessary and that psychology, not stock-picking, determines 90% of returns.

His approach: concentrate in AI infrastructure (Nvidia, Palantir) with a base of index funds, understand the product before the earnings report, and almost never sell.

The best thing to do in the stock market is almost always nothing.

Where the AI bubble actually is

• Hardware and data center infrastructure is not in a bubble — revenues are already following valuations.
• Software companies claiming to be AI companies are the bubble risk; expect some to crater.
• Not a dot-com repeat: major AI-era companies have real earnings backing their prices.
• Forward PE ratio (next 12 months earnings estimate) is more useful than trailing PE for fast-growing sectors; under 30 is a reasonable target.
• Understanding the product beats waiting for earnings — by the time news hits, the move is already priced in.

Portfolio construction for an average investor

• Replace the bonds allocation with more index funds rather than fixed income.
• Suggested split for a 35-year-old: 25% S&P 500, 40% Nasdaq 100, 30–35% individual stocks.
• Pick individual stocks from the top of those same indexes — they already meet quality criteria.
• Avoid the historic underperformers within the indexes; don't try to find hidden gems outside them.
• Gardening analogy: great returns come from stripping away the things that stop your best holdings from growing, not from planting more seeds.

Alex's actual portfolio

• ~40% Nvidia — held since 2016, bought dips including multiple 20–30% crashes.
• ~25% Palantir — bought at ~$11, trimmed at $25, re-entered at $28–32, now ~$135.
• Remainder: Nasdaq 100 index, SPMO (S&P Momentum Index), Google, Amazon, Broadcom.
• Treats index holdings as a "cash-like" position — sells shares held over a year to access capital gains tax rates.
• Income: ~85–90% from investments; YouTube and family office advisory make up the rest.

How and when to sell

• Trim, don't exit: reduce exposure from 40% to 25% rather than selling out completely.
• Dollar-cost-average out just like you dollar-cost-average in — sell 10–15% at a time.
• Never sell 100% of any position at once; sellers' remorse hits immediately after.
• Use proceeds to reinvest in indexes, keeping money working rather than sitting in cash.
• Holds less than 5% in cash inside the portfolio; 9 months of living expenses outside it.

Psychology and behavior

• Fidelity's best-performing accounts belonged to people who were dead — they never sold.
• Check your portfolio less often: weekly → bi-weekly → on payday → quarterly is the progression.
• When the market crashes, reassess what you hold — if you still believe in it, you should be happy buying more at a discount.
• Fear and greed index (CNN): a reading of 3 (extreme fear) during the tariff crash coincided with the market bottom.
• Panic-selling is a skill problem, not a market problem; every good investor starts by being a bad one.

Specific bets and themes Alex is watching

• Liquid cooling: Nvidia's Blackwell chips require it; enables more compute per rack, per data center — look at vendors supplying Nvidia, AMD, Qualcomm.
• Broadcom: makes ASICs that outperform Nvidia GPUs at narrow tasks; holding both removes the need to pick a winner.
• Holding Nvidia + AMD covers the entire GPU market; holding Nvidia + Broadcom covers data center chips not made in-house.
• Humanoid robots: skeptical — most industrial tasks don't require a human form factor; Amazon already runs 750,000 non-humanoid robots.
• Space: likely the biggest industry long-term, but outside a 5–30 year investment horizon.
• Crypto: holds zero Bitcoin currently; sold 6 BTC at $4,500 (bought at $1,500) — the opportunity cost lesson he cites most.

Platforms and resources

• Fidelity and Charles Schwab for serious investors — safe, established, auto-invests idle cash in money market funds.
• Robinhood and M1 Finance for mobile-first or automation-focused investors.
• For staying current on individual holdings: company newsrooms, earnings calls, Yahoo News, Simply Wall St.
• Dollar-cost averaging frequency: more often is better — weekly or daily smooths out bad timing; automate it.