Only you can answer this question for yourself. It also depends on what your household contents insurance covers.

What kind of insurance? If you have liability insurance, you don't need any.
It's the same as a bicycle that doesn't need insurance either
Except for bikes that go 45 km/h
have you need

Yes Insurance is very important

Liability insurance is sufficient to ride an e-scooter in Switzerland.
If you want more, you are sure to find additional insurance that incurs additional costs but covers more in the event of a claim.