Your trench looks awesome on you! I think you don't see it men often these days as many men dress like slobs and wear loose fitting shapeless clothes. In the U.S. where I live, men tend to wear trench coats for work in professional environments. After hours, it's sloppy clothes such as sweatshirts and hoodies which is what I see men wear these days. With COVID, the trend now is even more casual with Athleisure wear being popular. It will pass though, people will get sick of wearing stretchy clothes and looking like they came from the gym. The fashion world is ever changing, but the trench is a classic.
Also, not all men have the physique to wear a trench coat. You are nice and slim, and coat fits you perfectly. If you were plump with a big belly, it would not fit you as well, and you would probably steer away from it. Men who have a belly tend to purchase a straight cut car coat, or a short nylon zipper jacket.
The history of trench coats was made for men, for WW II, for the soldiers to stay warm and dry in the "trenches" while fighting, hence the nickname trench coat. Trench coats were not made for women, so a trench is definitely a man's clothing. It is a classic look, and to me, it is a very European look. I have a friend who lives in Paris, and he always wears his trench coat, with a scarf, and a beret (beret when it gets colder).
I love a man who wears a trench coat... The look is very confident look, a chic, sexy look without trying too hard. The slimmer cut is in line with today's fashion. Your trench fits your fashion look perfectly.
Even Burberry has made slim cut versions. You can read this short article and look at the photos of the men wearing the similar belted style as you... fits just like yours.
The 11 Best Trench Coats for Men in 2021 | The Manual
The trench looks great on you! Perfect on you in every way, sleeves down, sleeves up, scarf, no scarf.