(Even) Though I’m Japanese, I don’t know how to wear a kimono.

No matter how beautiful your kimono is, wearing the wrong one on anthat's inappropriate for the/an occasion could be embarrassing.

Though beautiful, the art of the kimono hais numerous disadvantagesot a task for the weak.

"not something for the weak" is an idiom to describe something as difficult and/or tedious.

First and foremost, it’s expensive because most of them are made of silk.

It’s also a demanding task becauseFurthermore, a kimono comes with countless accessories such as obi belts, obidome clasps, and tabi socks, which are allcan be easy to lose.

I think you could use "demanding task" to describe wearing the kimono in point 2 instead :)

Secondly, a kimono is a type of clothing that can be quite uncomfortable, and it can be quite a demanding task.

there is nothing wrong with your sentence, but you could say:

Secondly, wearing a kimono may feel uncomfortable to some.

here, you are saying what makes it uncomfortable. is it a feeling of wearing it?

Simply put, wearing a kimono meaninvolves wrapping multiple layers of clothes tightly around yourone's body.

we usually use "it means" when talking about definitions. involve would be a better word here!

when you are writing a blog style post, we usually don't use "you", but rather, "one's".

Basically, it’s nearly impossible to wear a kimono properly by yourself unless you’re trained to do so.

No matter how beautiful your kimono is, wearing the wrong one ton an inappropriate occasion could be embarrassing.

In conclusion, you need considerable knowledge, a certain level of physical health, and quite a loto invest a good amount of money to wear kimono properly.

invest: used when you are doing something/spending money in something for the future.

I’m confident that the day will never come when I live a life wearing kimono every daThe day where I wear a kimono everyday will be the day when pigs start to fly.

pigs start to fly: is an idiom, to say that something will never happen. (because pigs will never fly)

Though I’m Japanese, I don’t know how to wear a kimono.

I would rephrase this to "I don't know how to wear a kimono even though I'm Japanese." or "Despite the fact that I'm Japanese, I don't know how to wear a kimono.".

How sad is that?

The rest of your post reads like an essay, and the difference in formality between the rest of your post and "How sad is that?" is a little bit jarring.

It started as sadness, but now it has turned into anger.

Similar feedback here as for your previous sentence.

Secondly, a kimono is a type of clothing that can be quite uncomfortable.

I would rephrase this and the next sentence to read "Secondly, since wearing a kimono means wrapping multiple layers of cloth tightly around your body, it can be quite uncomfortable."

To prevent it from coming loose when walking or sitting, you usually need someone’s help to tie the obi firmly.

I would rephrase this and the next sentence to read "Since you usually need someone else's help to tie the obi firmly to prevent the kimono from coming loose when walking or sitting, it's nearly impossible to wear a kimono properly by yourself unless you're trained."

I’m confident that the day will never come when I live a life wearing kimono every day.

When writing formally we don't tend to write directly about ourselves.