SimonM’s analysis is great—a hugely important point he covers well is that in the real world you don’t know exactly what your edge is.
And whenever you’re considering betting in a context like a highly liquid prediction market—you’re playing a negative sum game against competent adversaries. So for most people not only are they wrong about the size of their edge, but their edge is actually negative.
By default people have a bias towards risk aversion, which helps cancel out a bias towards overconfidence they can beat the market.
But I think it’s still important to notice that, if you’re someone with a safety net and/or future earnings to look forward to—you should in principle be willing to tolerate very high levels of risk as long as the expected value is positive (while still admitting the EV of day-trading options is negative).
The two world models:
“There’s lots of alpha to be found, but my utility as a function of money is very curved and I’m terrified of losses”
“My utility as a funciton of money is relatively flat given my substantial future earnings and safety net, but I don’t actually have an edge when it comes to financial markets”
Both advise against making reckless bets in financial markets. I claim for most of us number 2 is closer to the truth.
The practical implication—in situations where you get the opportunity to take +EV risks and you’re not subject to adversarial efficient market dynamics—you basically want to load up on risk to a degree way higher than what feels comfortable .
When a game is asymetric, non-zero-sum, and you don’t have competent adversaries trying hard to screw you—you really will find legimitate edges. This is where it’s appropriate to be extremely bold. And most of the time these prosaic “bets” have an inherently capped, relatively small bet size anyway.
Stuff like
Spending money on cleaners/babysitters to free up time to work on speculative on side projects
Hiring a tutor
Spending time+money to attend a networking event
Posting online under your real name
Spend money on products which may or may not work (e.g. a gadget that’s meant to help you sleep)
Asking for more money before accepting a job offer
Asking to pay less money before signing a contract to buy a house
Even mundane stuff like asking for an introduction or telling a joke that might not land
In my view the optimal policy for privlidged young people is usually avoidance of stuff like prediction markets (unless an absurd opportunity arises), while at the same time seeking to take an abmormally high level of +EV risk in positive-sum non-EMH domains.
Maybe it would help if you construct an explicit concrete model? You’re welcome to define what future opportunities will come along after this bet (or even a distribution of possible future opportunities)
Are you claiming that after you build this concrete model—Kelly betting will emerge as the objectively optimal strategy regardless of the agent’s preferences and regardless of whether we add a safety net/income stream into the picture?
Or are you making a softer (seemingly irrelevant) claim about what happens with geometric means/average growth rates when we don’t account for safety nets and income streams?