There's no light underground. Also, tunnels collapse. Also, some air is stale or poisonous. Also, if you climb down a shaft you can't always get back. Also, emergency services can't reach us...

Also, we cannot carry enough supplies on our backs. Also, the deeper we go, the more likely that caves are full of water. Also, caves are often just inches wide, so you can get in but not out. I could go on and on!
Uncle says modern equipment and supplies are lightweight, and we can use wind-up torches, and he expects to find some resources underground, and we are simply seeing if Saknussemm already did it or came back... he has an answer for everything.
Should I get somebody else to persuade him? Or just accept my fate? Or do something else?