99.9% of the time, paying with bitcoin goes through a payment processor such as bitpay, bitpay instantly sells your bitcoins for FIAT hence putting sell pressure on the market. So basically if people take your advice right now and start buying products with bitcoins, the price will fall.
but if there are enough people using bitcoin for their transactions, shoppings, the price of Bitcoin does not fall, because most of thes coins are in circulation.