if it makes you more than $20 or saves you more than $20 then it’s worth it. Simple as that. That’s it. That’s the test. For some, the time they save and spend with family is “worth” $20, for others, productivity increases don’t lead to free time, while others still don’t have $20 to spend.
Fwiw I get my teeth professionally cleaned once a month and spend more than $20 on it. Because it’s worth it to me and because dental care is expensive. Toothbrushes are cheap not because they’re worthless but because they’re undifferentiated. All toothbrushes are the same. ChatGPT… isn’t.
If he wouldn't pay $20 a month to prevent tooth decay, he clearly is the type who knows the price of everything and the value of nothing.
> What kind of crazy value would you expect something to have in order to be worth $20/mo?
The implication of that is that of tootnhcare cost more than $20 a month he wouldn't do it. Which is crazy, the expected return from brushing your teeth is well above $20 a month.