Earlier quoted context omitted.
> I'd gladly pay 5k for a robot that can auto-organize my stuff around the house The main equation for general-use household robots is: can it beat human fares? A good weekly cleaner (4 hours) is about €22/h in Paris, or €4.5k/year. Let’s say your robot lives 4 years, similar to your computer (which seems fair, since it is one, and an abused one at that). Since you amortize its price over 4 years, its initial cost mu…
- The robot is in your house the whole 168 hours a week, not just 4. You're assuming a good cleaning robot would be absolutely useless for anything else, like cooking, laundry, etc. - 4-year robot lifetime is overly pessimistic. If upgrade is not the reason (which has nothing to do with lifetime, it's your choice to upgrade), a robot could last way more than 4-years (especially with right-to-repair laws in place). -…
I find interesting to address the middle one statistically.
A given machine has a number of random events that can kill it. Each possible event type i can be modeled as a Poisson process Xᵢ with, in a given year, probability λᵢ. The machine survives in a given year if no occurrence of event i happens, with probability Pr(Xᵢ = 0) = exp(-λᵢ).
For instance, a device with an average lifetime of 8 years and a single possible cause of death, has λ = -ln(½^⅛) = 0.087.
Given N independent event types (say, if you have on the order of N components), the yearly survival of the overall machine has probability Πᷡᵢ exp(-λᵢ).
Thus the lifetime of the overall machine is ln(½)÷ln(½^(Σᷡᵢ 1÷Lᵢ)) = 1 ÷ Σᷡᵢ (1÷Lᵢ) if each component has lifetime Lᵢ.
For instance, two components with an average lifetime of 8 years yield a single machine with an average lifetime of 4 years.
The more death-causing event types there are, the smaller the lifetime; and a general-purpose robot inherently has more.
I believe this result is counter-intuitive, and is the reason you might be led to think I am overly pessimistic.