When you Hodl you are effectively loan out the amount equivalent in FIAT that that BTC represents to the market cap, and thus others to do things with that capital [the amount maybe the amount you acquired the BTC for]. Either way it is incorrect to say that not spending BTC is not Using BTC.
For now, I think that the best way to use bitcoin is just to hold because of the volatility in the market, Spending bitcoin is not really the thing for now because it is still in the process.
In the future when the market price is already stable I think it would be suitable for spending but personally, I think it's better to invest your bitcoin than investing it online.
Nothing really could go wrong if you're holding your bitcoin for a long term investment, and you could always sell it whenever you want as the market price increases.