I'm aware of "buy-and-hold index fund investing". I believe it
was a good strategy because it was an an unpopular, undervalued asset class 100 years ago and has since become very popular and overvalued.
Another important consideration is that companies now go public much later than they did pre-Sarbox. The sad truth is that a company's biggest gains are generally behind them by the time retail investors are allowed in. There will be no repeat of the windfalls ordinary investors made[1] from the IPOs of Microsoft, Walmart, Starbucks and similar companies in today's batch of new IPOs. This in itself is a good reason not to reflexively discourage someone from learning about angel investing.
> I am also bewildered that you'd think buying index funds is good in an up-economy but is bad an a down-economy.
I don't think this.
Provided long-term real-GDP growth prospects are good, I think buying index funds when the funds themselves are under-valued is a good strategy. Looking at the underlying P/E, P/B, DCF or just about any metric you choose, you'll see that on average, publicly traded stocks[1] are very expensive compared to historical valuations.
1) both directly and through funds that index them