Wandering in the wilderness was mercy, really. The ten doubting spies who said we can’t do it, were telling the simple truth. They couldn’t do it. They had no faith to do it. They knew they’d never survive a fight with giants.
Well, they didn’t survive any way, not even to wander in the wilderness for forty years. They died of a plague.
Unfortunately, before the plague struck they persuaded many others they couldn’t do it, and of course then those people couldn’t either. The plague would have killed those unbelievers too, except for the intercession of Moses. Except for God’s mercy.
In God’s mercy, they didn’t have to fight the giants. But they weren’t allowed to ever enter the promised land. Instead, for forty years they were allowed to live out their lives, raise their families, build tent cities wherever they camped, tend to their herds and flocks. They didn’t even have to plant crops. Humans and animals were fed supernaturally, boring as they thought manna was, unless the animals found enough forage to survive on. I suspect they ate manna too.
Part of their time was spent attending and tending to the Tabernacle of Moses. Part of their time was spent assembling and disassembling that Tabernacle, carefully carrying it from place to place. Whenever God moved, they moved. Once at a new camp, they had to re-assemble the Tabernacle, then bring the animals and make the sacrifices, all the while repenting and praying and hoping for the best. Counting down the days, probably.
Eventually those unbelievers, whose clothes didn’t wear out, whose shoes didn’t wear out, who didn’t have to go to jobs, didn’t have to plow fields or plant grain, didn’t have to build houses or cities, didn’t have to wage war against the giants, died of old age and were buried in the wilderness.
Their children were allowed to enter the promised land, however. Of course they would have to confront a few unruly, uncooperative and combatant groups of people along the way, as well as dispossess the inhabitants once they got there. It’s a good thing they had Joshua to train them in warfare. A real good thing that Joshua — the warrior and spy — wasn’t one of those who had brought back an evil report.
The point of this story is, wandering in the wilderness for forty years was a mercy God showed to the unbelievers in response to Moses’ intercession. Sometimes mercy wears unfamiliar clothes.