I believe the main utility for all cryptocurrencies including bitcoin is online payment. it's way easier than going throught the entire banking payment process flow, and saving a bit of money from for lower fees .
However, since bitcoin haven't stopped rising in value since day one of it's creation, people tend to hold, considering it as a '' safe investement ''. It was prooven at multiple occasions that spending bitcoin will eventually turn out to be a wrong decision. I personally believe that spending bitcoin should not be considered as a first option as it keeps gaining value.