I think these concepts can be very dangerous if applied too liberally. In both examples you need to have a rough understanding of how happy the thing might make

I think these concepts can be very dangerous if applied too liberally. In both examples you need to have a rough understanding of how happy the thing might make you feel, or how much "value" it's going to provide. I can buy A for £50 or B for £100. B is in some measurable way "better" than A, but I can't quantify how much. B being better might make me use it more? it might also be used equally little and be a waste of money. Growing up poor and becoming comfortable financially as I grow up has only made these sorts of assessments much harder I've found.