It's about returns
Well, it was exactly my point that for some investments it is NOT about returns. Sometimes you just want to make sure that you won't loose the wealth represented by an investment. If you own, say, $10M then you would NOT want to run any risk over this money. You might allocate a part of it to a "high return" portfolio/trading algorithm, but for the biggest part you would want to ensure that you don't loose the wealth represented by that money.
Here the question of money versus wealth arises. Keeping the $10M in cash for example is NOT a good idea if you want to keep the wealth it represents. Inflation will destroy that capital quickly. Hence you need to invest in something be it shares, real estate, gold or paper napkins.
Best,
Rien.