As a general rule, having personal liability insurance is a good financial move. This is especially true if you travel, play risky sports, have an active social life, own pets, or otherwise engage in activities that carry a risk of creating legal liabilities.
Many Swiss landlords require you to have personal liability insurance in order to be eligible to rent their property. Having this insurance as a renter is generally advantageous because the likelihood of damaging your rented home is relatively high.
What is more, the premiums you pay for personal liability insurance are relatively low.
If you live with other someone else (a parent or a romantic partner, for example) who already has a personal liability insurance that covers their whole household, then getting your own liability insurance is not necessary.