I have the same problem. I think It's because we already got used to treating Bitcoin as an asset to invest in, not actual money to pay with.
Bitcoin is still undergoing transformations to become a new currency, so we still need some time to accept that bitcoin is not just stock to invest in, but the money of freedom that won't be controlled.
When I want to pay for something with BTC I'm thinking about its price and feel like "why am I spending it right now? It will go up and I will have more money if I will just hold it." So yeah, I have the same problem haha
Since bitcoin was created, bitcoin has been the currency of the world, it doesn't need extra time to convert into currency. If you are looking at bitcoin as an investment, it is your behavior towards bitcoin, bitcoin is not quite an investment. But for bitcoin to become the unregulated world currency, it will be very difficult to do. I mean, bitcoin is already currency, but to be legal and recognized by the government, that will never happen.
You can treat bitcoin as an investment and not need to spend it, as it is your bitcoin, but there is nothing wrong or unpleasant about using it instead of fiat.