The legwyn event can only be done once roughly every hour. It requires quite a lot of effort to log in every hour, complete the event to spawn the enemies (unless you are a dick that let’s other people do work for you) and kill all the enemies. Even if you wait for other players to do the event you still have to actively check when it starts. And you will be less likely to have a full group, meaning you get even less money.
Also, the amount of silver you make is based on how many players are present. When the game is released there will be a lot more players than there are now, meaning you will only make a small amount of what you are currently making .
Not to mention that there is most likely going to be much better places to gain silver than legwyn once all the content beyond level 200 is released.
You don’t need multiples computers to start multiple instances of a game.