Soo is the older brother planning to commit suicide?

He probably plans to win money in a gaming competition or something. To show his younger brother he is something

Ohh yeah thats a good explanation lol. I mustve misinterpreted it. It just seemed like he's thinking he's a disappointment and useless and a burden to his younger brother. And the date in the calendar along with him counting down the days made it seem like he's counting down days until he kills himself and will no longer be a burden to his brother and drag him down. At least that was my interpretation

Yes it's a little confusing but it shows that he's proud of his little brother and the accomplishments he just made for winning first place with his manga sterilization and so he's doing what he's good at which is gaming and theres probably like some type of competition with money involved and he's practicing and counting down the days till the competition, it's just a guess tho I'm not sure what's gonna happen next.