Is building insurance for a garage reasonable?

Hello everyone,
my name is Marc, I come from the beautiful NRW and I have a vice: cars.
To be able to store them all, I have garages here and there, mostly in already existing properties, homeowners associations...
Now I have bought a garage from 1970, spruced it up inside/outside, and re-roofed it.
Unfortunately, this garage is not insured to date, at least not from a building perspective.
Basic inventory would certainly be covered by my household insurance, but there is only my car inside here.
Of course, I have private liability insurance, naturally also one for landlords.
Now I wanted to include the said garage in the building insurance policy of my house, as it is about 400m as the crow flies away.
However, according to the insurance agent, this is not possible; he offered me a new building insurance that would insure my garage for €120/year.
I actually find that steep because not much can really happen. But I was told that there is probably a minimum premium.
Now I have the following question, which I actually never asked myself regarding any of my properties: do I even need building insurance here?
Or is my insurance just “complicated”?
Right now, I’m unfortunately a bit stuck. It’s not that I couldn’t afford the €120/year, but is it even worth it?
Do you perhaps have a tip for me?
Best regards and thanks,
Marc

Garage built in 1970 purchased, renovated inside/outside, the roof redone.

Do I even need building insurance here?

You are not telling us the most important thing: what kind of garage is it? Where, detached? Size, etc...

because actually not much can happen

Who says that?

What do you want to insure the garage against? Building insurance typically covers fire, storm, water damage from pipes, hail, and possibly natural hazard damage.

What kind of garage is it?

What's it actually about? Is the building important to you, or the car inside it? Those can be two different products ...

Hello everyone,
first of all, it is important to me that damages caused by my garage are covered.
By the way, the garage is a precast concrete garage, which stands in a row with 7 others.
Almost all of my cars have partial coverage, and there is actually no tool present.
Therefore, I see the risk as being a storm, hail, or other things that could cause damage. I don't really see water or electricity as a threat. But since the garage has little that could break, I am now wondering what makes sense.
Best regards,
marc

Precast concrete garage and roof newly covered. I don't understand it.