I'm not what there is to believe in mask effectiveness?

There are studies about it.

You don't get infected with COVID just because it's a mix of your own immune reaction, the amount of particles etc.

A mask is really easy to wear and reduces your risk.

I'm not advocating for mask mandates at this point or let's say I don't care about it but if you want to reduce the risk of having COVID while on holiday, I would suggest trying to wear a mask.

Independently of it, in Germany the hospitalization is currently high and plenty of personal is sick. I still don't want to be in a situation of having something really bad and having to be in a hospital right now.