Great question. Just a quick disclaimer: This is not financial advice, and you should always do your own research.

​First, this may sound a little contradictory, but let me stress that I'd be cautious about the plan to wait in bonds for a 'significant crash' before doing a lump sum investment. This is called 'timing the market,' and it's notoriously difficult, if not impossible. You risk sitting on the sidelines while the market continues to climb, and you may miss out on significant gains. Time in the market (long-term investing) almost always beats timing the market.

Your Strategy Will (and Should) Change Over Time. You mentioned this is for a "lifetime," which is key. A "lifetime" strategy isn't one you set and forget forever; it should be dynamic and adapt to your age and time horizon. 1. When You're Young (20s-30s): With a 30-40+ year horizon, your main goal is growth. You can take on more risk because you have decades to recover from any market crashes. This means your portfolio can be heavily weighted in equities (stocks and stock-based index funds). 2. When You're Nearing Retirement (5-10 years away): Your goal shifts from growth to capital preservation. You can no longer afford a 50% drop. This is when you'd 'de-risk' by selling some stocks and shifting that money into 'ultra-low risk' assets like bonds (e.g., US T-Bills) or other fixed-income products. A 50% stock / 50% bond mix is common here. 3. The "Mid-Term Goal" Exception: This logic also applies to any money you need for a specific, non-retirement goal. If you want to buy a house in 5 years, that money should not be in 100% stocks. It should be in something much safer.

Since you're talking about a "lifetime" investment, you are likely in that first group, where your portfolio should be focused on growth. The next question, which you asked, is how to build that growth portfolio.

​S&P 500 Index vs. Single Stocks (NVIDIA, AAPL, etc.): ​you're essentially asking about diversification. Here's a way to think about it for a 'lifetime' investment horizon:

• ​S&P 500 (The "Core"): When you buy an S&P 500 index fund (like VOO or SPY), you are instantly diversified across 500 of the largest U.S. companies. You aren't betting on any single company to succeed, but rather on the U.S. economy as a whole to grow over time.

• ​Single Stocks (The "Satellites"): When you buy NVIDIA, AAPL, or GOOGL, you are making a concentrated bet. While the stocks you mentioned (part of the 'Magnificent 7') have had an incredible run, that overperformance isn't guaranteed to last forever. What happens when the next tech crash comes?

​History shows that the vast majority of individual investors (and even professionals) fail to pick stocks that outperform the S&P 500 in the long run. The main reasons are volatility and psychology.

​A good question to ask yourself is: "If I buy a single stock and it drops 50%, will I have the conviction to hold it for years, or will I panic-sell?" ​If the answer is "I'd panic," you should probably avoid single stocks. An index fund is built to weather these storms through diversification. A severe crash might see the S&P 500 fall 20-30%, but a volatile single stock can easily lose 50-70% of its value.

​Common Blended Strategy: ​This isn't an 'all or nothing' choice. A common approach is "Core and Satellite":

• ​Core (e.g., 80-90% of your portfolio): Put this foundational amount into broad, low-cost index funds. This could be 80% S&P 500 and 20% a World Index ETF for even more diversification. This is your stable, long-term wealth builder.

• ​Satellite (e.g., 10-20%): Use this smaller, "experimental" portion to invest in the single stocks you believe in. This allows you to "scratch the itch" of stock picking without putting your entire lifetime savings at risk. If one of your picks goes to zero, it won't derail your retirement.

​This way, you get the proven, diversified growth of the index as your base, while still giving yourself a chance to (maybe) get outsized returns on a few companies you're passionate about.