The people on the island survived so long because Griffith and the others didn't know they existed. Now they do and the island people could've died. So instead of waiting to meet Griffith's monsters a second time they're leaving this world.
Why did it end so abruptly? Is this an ongoing thing that hasn't been finished or translated?
On another note, I agree with the tutor. Working is hard is good. You should work hard. But have a goal, to. If you're the workaholic type, don't forget to take a break. If you're the lazy type...
@glomoro
I think it's to reduce the number of people that handle the money. Like in some arcades where you pay real money at the front and they give you tokens instead of quarters.