if you are using bitcoin then maybe today 1 apple is 0.0008 btc , but tomorrow with 0.0008 btc you can buy 2 apples, but if no one used bitcoin for shopping then there won't be any shop that will adopting bitcoin anymore
so what will be you choice?
I will prefer to use which one will be beneficial to me in terms of cost because that same 0.0008btc that is now buying 2 apples today might end up not even buying one the following day but same cannot be of Fiat. What I will do is consider the cost if I change in to Fiat and then buy compared to when I buy directly with btc then from there I decide which one to go for...