I so love that everyone underestimates him and he allows them to and takes care to hide his strength. Until he doesn't then just whips out a can of whoop ass and takes what he wants to amuse himself.
This is a very stereotypical xianxia plot, but funnily enough, this is the best of that genre ive seen in manga format, maybe because its korean not chinese LOL
If he already killed everyone in the sect (or at least all the mooks in the sect like he said he would) then there isn't really a sect left now is there.