I cannot find any real reason why you should spend your bitcoins in order to shop online.
In my opinion, Bitcoin has a bigger value than the one right now so it is not worthy spending them for shopping. It is better to keep them in your wallet and consider it as your investment. If you want to buy something online use a stablecoin...
Let's just say some of us just want to increase the global usage of bitcoin as a peer-to-peer payment currency. Imagine if every single one of us is just holding bitcoin without spending it from time to time. Pretty much expect every single online store/service to stop accepting bitcoin payments. What happens to adoption then?