@Seprious
> My small brain can't follow what is happening anymore
The man with the scar adopted Siwan because he thought he was a kung-fu genius born with talent. His own kid wasn't strong enough to rise up the ranks and take over the gang. He believes that only those with talent can beat those with talent. Then he found Siwan, a ten year old who managed to beat six senior (?) gang members in a 1-on-6 fight. Siwan had, in his eyes, talent.
However, as revealed in the cell phone image, it turns out that "Master" was the one who actually defeated the gang members. That is the "lie" Siwan is constantly referring to in this chapter. Now scarface is cranky because all his dreams have just been smashed.
NB: talent is a natural skill at something. It's different from working hard to become good at something. The idea of this chapter is that the man with the scar (I genuinely cannot remember this dude's name!) thinks that only those born with talent can surpass others born with talent.