I think bubbles are things people see with 20/20 hindsight. If you look at any particular period where prices go up and then they go down, you will always find people who predicted that they would go down. Those are the people you pay attention to.
Active investment is a zero-sum game. Passive managers don't play the game. They buy something resembling the market as a whole, or some segment of the market, and they don't respond to the actions of active managers.
Economies typically do not function well in hyperinflation. The real value of government debt might disappear, but the economy is likely to disappear with it.
People think rationally that the world really is more risky. Imagine in 2008 that investors thought there was a 10% chance we'd have a depression. That would partly justify the drop in prices.
After costs, only the top 3% of managers produce a return that indicates they have sufficient skill to just cover their costs, which means that going forward, and despite extraordinary past returns, even the top performers are expected to be only as good as a low-cost passive index fund. The other 97% can be expected to do worse.
In my junior year in college, I was getting kind of tired of French. So, I took an economics course, and I loved it. The rest of my two years in college I spent in economics.
