yeah.. that won't work. variables are globally stored in the same file, therefor if one player was to type /toggledrop it'd disable it for all players, and if it was already disabled it'd enable it for all players. use either the player's ign or the player's uuid inside of the index of the variable (uuid in case the player changes their username.).
//EDIT: I misread your original post, it would work, just not in the way he wanted it to. He asked for it to be player specific.
You also shouldn't set the variable to false, what you should do is delete it when you're disabling it. this will save up space in the variables.csv file and is generally just a better habit.
command /toggledrop:
trigger:
if {ToggleDrop::%player's uuid%} is set:
delete {ToggleDrop::%player's uuid%}
send "&3&lDrops &8| &bDropping items is now &aenabled."
else:
set {ToggleDrop::%player's uuid%} to true
send "&3&lDrops &8| &bDropping items is now &cdisabled."
on drop:
if {ToggleDrop::%player's uuid%} is set:
send "&3&lDrops &8| &cDropping items is current disabled! Please use &n/toggledrop&c to toggle this option."
cancel event