Cultivation is an arduous journey; a disciple will eventually have their own social circle, no one can cultivate successfully while hiding in a greenhouse.
If those alchemists from the Wenjin Sect had known of elder brother's talent, or even witnessed elder brother's skills in alchemy, they would have been much less envious.
Because they would have given up, not thinking that master accepting elder brother as a disciple was a stroke of luck, but rather that elder brother's talent in alchemy greatly surpassed their own.
They would clearly understand that even if elder brother died, master wouldn't take a liking to them.
This is precisely the purpose of master holding this Alchemy Competition, to let the alchemists of the Wenjin Sect, and even those in Wenjin City and other cities know.
Master accepted me as a disciple because of my talent.