Owners don't have to have it. Tenants' legal obligations differ depending on the region. In Flanders, tenants have been under a legal duty to take out property insurance since 1 January 2019. Wallonia made tenant's insurance compulsory on 1 September of this year. Brussels has not yet officially gone that far.
But you should never be without it, because it's not just there for you in case of fire.
It's a vital overall safeguard for the building you live in,
and for the home you make in it.