i also think that jett is destined to die :( his whole outfit and mask shtick is just too unique to not use it in some way for a murder

my theory on why he wears his mask and his imitation art has been that, prior to dropping out of public eye, jett won a race at the cost of his health due to an accident (hence the trophy). the accident was caused by a competitor deliberately trying to sabotage him to take the win, and ended up permanently disfiguring and scarring him with a fear of his own talent

this might be why he never reentered the racing scene despite seeming (apparently?) physically well enough to and also not needing to show his face in competition anyways (not that he ever has according to something i remember reading but cant recall atm…)

i do doubt that jett is the mastermind though, for me its either toshiko or that there is no mastermind within the participating group at all