There are large amount of He-3 on the Moon, which will be used in nuclear fusion technology.
It is widely regarded as the energy of the future.
D-T fusion is easier to achieve than D-He3 fusion. And we will not see commercially viable D-T reactors until 2050 (according to those who build ITER).
The only advantage D-He3 fusion has is that the energy gain is a bit bigger and more importantly that there is no neutron radiation and therefore
no shielding required. Which also means no radioactive waste, although the waste from a D-T reactor is realtively harmless (approx. 100 years storage required).
So mining the moon for He3 is mostly a wet dream of space fanatics, and not something we will see this century.
And even if it will be done at some point in history, its gonna be robots who do the mining, also because the moon is near to earth which allows
remote control by humans in critical situations.
It's the prestige as well telling the world that you are now a major player, beyond having a big army and industry, but scientifically, as well.
Going to the moon 50 years late is not really prestigious, its rather an embarrassment. Technically its not a challenge anymore (well, still a challenge but you know what i mean..).