Because the boys’ hole is now big enough.
Added to answer some questions:
When I asked one son awhile back, “Why?” he said, “Because we’re boys.” That’s the clearest explanation they can give. They have been unearthing big rocks, which seems to be the goal of the moment.
My husband couldn’t care less. Our backyard is quite untamed and dominated by a giant Rainbow play structure and edged by overgrown laurel hedges. (They kids play inside the hedges which are just beyond the hole.)
The dirt has been spread down the little slope just below the hole and mounds up now on the sides of the hole.
I’m hoping they lose interest soon so I can refill it . . . but I can’t see a reason to make them stop.
Also, the in the picture, only one of those boys belongs to me. The others are neighbors.