My 2 cents: stocks indexes are a good investment as long as you don't only rely on them. Even on a >10y period, they can perform poorly or amazingly well, depending on factors you have no control over. I don't like lack of control.
To further this discussion, what do you suggest for long-term investments that you would have more control over? Real-estate (landlording) is one block in our portfolio
By "lack of control", I mean stock indexing investment shines as much as the market wants it to shine. If Mr. Market gets depressed, you (temporarily) lose money, even if he's wrong and investments are actually sound. Anything that mainly depends on speculation incurs a lack of control, by definition.
There are a few investment strategies that give you a little more control, in the sense that you don't only depend on what other think your investments are worth :
- landlording, as you mentioned it. Whether the market believes RE is booming or busting, whether your building's market value goes up or down, rents keep coming. If they stop coming, that's because your investment was bad, not because the market thought it was bad.
- dividend investing, or even dividend growth investing. That's quite the same as landlording : your businesses keep producing and giving you cash, no matter what other investors feel.
- High yield bonds work quite the same, too.
- Massive diversification across asset classes also kinda works. In this league, I like the permanent portfolio a lot. When you only (or mainly) own stock indexes, you need the economic context to be favorable to stock markets (i.e overall prosperity, whether real, perceived or anticipated). If you own at the same time stocks, govt bonds, gold, and/or a few other things, you know at any time, some of your investment will produce money: when investors on the stock market panic, they "fly to safety" (treasuries and/or gold, depending on the context). This way, you're not a victim of speculation and volatility: you make a profit from it. I like this strategy, although it is not for everyone.