Helium 3 on the moon is very much like spices in the New World. If it provides a decent justification to get there, you might forgive that we’re heading in a potentially wrong direction.
Helium 3 is rare, but not that rare. You can purchase, at an elevated expense, a tank of pure Helium 3. Despite this, we have yet to run a working fusion power plant that burns any fuel. Not deuterium, not helium 3.
Mind you, there are plenty of other things that can be done on the moon that will likely be useful, so exploring the Moon will very likely be proven to be useful. You will get far fewer complaints building a mass driver and mine on the far side of the Moon than you would trying to build a mass driver anywhere on Earth. It’s also technologically easier with less gravity and no atmosphere. Thus, for building large things, it’s much more reasonable to build them from lunar materials.
Furthermore, just planning a base on the Moon is valuable. We can breed generation after generation of fruit flies or mice or other animals, to see how they deal with low-gravity, for example, and compare them to Earth-based control groups. We can also compare them to a low-gravity centrifuge and see what difference that makes.
The Moon is a huge rock. Radio waves from Earth don’t propagate through it, so the far side of the moon makes a great place to do radio astronomy. Especially SETI sort of tasks, given that it’s fairly rational to assume that the same radio waves we find most convenient they will also find convenient.
In my mind, the biggest resource available on the moon is a wide variety of useful materials. There is plenty of titanium and aluminum and iron there and all of it’s at fairly easy access with the ability to build a mass driver without being in somebody’s backyard. And you also don’t need to worry especially hard about rendezvous windows for near-Earth asteroids.