> people on Hacker News tend to be smart enough to understand how to estimate probability distributions and how to compute expected value off of these estimate

That's a strange assumption to make. If anything, I'd argue that people who think they are somehow smarter than others because they're an engineer/programmer/whatever are more likely to put too much faith in their intelligence and make financial mistakes.

> His advise is the rational approach

Being smart is orthogonal to being rational.