Thinking from a general, layman's perspective, when one cannot properly assess the risks of a particular situation, but still wants to apply probability to maximize chance of gains, how can one use the Kelly criterion's investment formula to maximize gains in a simple and relatively mathematically thoughtless way?
While it is true that without knowing the odds and without doing the calculations, it is impossible to maximize the probability of maximizing the probability of gain, this does not preclude that the greater the complexity, the decreasing rate of return for the effort invested in determining the probability maximization.
This is to say, that one may guess a probability which is more or less in line with little effort, but to come to the most precise outcome, one must put in an exponentially increasing amount of work for a decreasing rate of return.
For example, I considered that a possible rule of thumb when the probability is unknown but expected to have some or even a lot of risk, would be to use the Kelly criterion's investment formula using a fixed high probability of failure, such as 90% or higher, in order to minimize the risk that the median would decrease and maximize the chance that the median would be above the starting investment.
Considering that the odds of any outcome are unlikely to be zero or negative, and assuming that the odds will be higher than zero or else there is no way to win regardless of the outcome, then what is a good way to minimize risk with as minimal calculations as possible, when the probability is unknown, even if the outcome is less than optimal?