There were many security workers at every intersection, and a large crowd of audience members wasere heading towards the concert.

Maybe only young people, who have time, money and energy, are suitable for the concert.

Maybe I'm not the target audience, as I'm much older than the typical concert - goers.

However, during the concert, I took my wife there to see the scene outside of the concert.

In Chinese, we have a phrase “啃老族”, which means that young people don't work, but live relying on their parents.

The audience members wore fashionable clothes and colorful makeup, dressing themselves in a cutting - edge style.

Maybe only young people, who have time, money, and energy, are suitable for the concert.

They danced, shook their heads, and sometimes made exaggerated gestures.

Maybe I'm not the target audience as I'm much older than the typical concert - -goers.

Words linked with a dash rarely have spaces like this.

However, during the concert, I took my wife there to see the scene outside the concert.

Not wrong at all, but saying "the concert" twice in the same sentence feels a little awkward. You could say, "However, while it [the concert] was going on, I took..." or maybe you could say "...to see the scene that was outside."

I guessedthink they were either in college or high school.

Yet again, not wrong at all, but "think" sounds a little more natural here than "guessed". Although, "think" is present tense, so if you want to emphasize that this is what you had guessed in the past, "guessed" or "had guessed" would still work better.

I wondered if some of these concert - -going teenagers were like this, considering the money they spent on tickets and trendy outfits.

The audience members wore fashionable clothes and colorful makeup, dressing themselvesed in a cutting - -edge style.

"dressing themselves" implies that the audience members are changing clothes right there on the spot, which probably isn't what you mean. The act of dressing themselves had happened already in the past, so it would be "dressed".

I later learned from social media about how they behavhad acted at the concert.

I feel like you want to imply that some time has passed. That is, a few days after the concert, you saw what had been happening inside it on social media. If so, I'd add "later" before "learned".
Another alternate way you could say this, by the way: "I would later learn from social media how they had acted at the concert."

The rest of my corrections here are pretty minor. You don't need "about", but it isn't really wrong to have it either. And, because the concert at this point in the story is now in the past, it feels slightly better to use "had" before "acted"/"behaved". But yet again, leaving it out still doesn't hurt.

"Behave" means something similar to "act", but comes with it a sense of judgement upon the person doing the action, especially upon children or very immature people. "behaved" works if you mean to have this sense, but otherwise I would say "act".

They danced, shook their heads and sometimes made exaggerated gestures.

When you say "exaggerated" here, do you actually mean "vulgar" or "inappropriate"? Are these gestures which would be incredibly disrespectful in many situations? If so, "exaggerated" is an odd word choice. But if they're not particularly disrespectful and are just extreme or eccentric, "exaggerated" does work in this situation.