The Answer is: It is their only way out.
"Yes," replied the Professor, looking at me calmly from under his spectacles, "it is the only chance which remains to us of ever escaping from the interior of the earth to the light of day."
Well, I old man will feel happy if he has achamplished everything he ever wanted in life. Hope this helps :p
D. Pre-owned vehicle I think but I’m quite dumb so I’m not too sure
Some people on earth, don't get enough water everyday and they have to walk 5km at least to get a bucket of filthy water. So people who have clean water everyday sometimes waste it and pour it into a drain. However, they do not think about the people who actually need it and they take it for granted.