The brain finds it comfortable to shut down when faced with too much complexity. To fix that, we have to simplify, even if that requires a small sacrifice in accuracy
Longevity risk, taxes, financial repression, unexpected high inflation, career risk, and psychological factors make it very difficult to save enough for retirement
Both personal investing and PE investing force one to accept relatively concentrated portfolios, deal with significant information asymmetry, make medium-term decisions that are difficult to reverse