Sending manned mission to the Moon isn't a long term goal, nor is a manned Mars.
Mining water in space should be a short term goal.
And harvesting power from space for use on the earth surface should be a long term goal.
Mining water in space is related to the goal of getting energy from space, and before
getting power from Space to earth, we need large scale energy production in space
which in electricity is sold in space for space activities.
Converting water into rocket fuel is one use of power generated in space.
Another use of electricity produced in space is beaming power. If you can buy
beamed power in space, there could many uses.
Beamed power is particularly useful if one needs power for a short time period.
Such as when establishing a base of operation, or if one needs peak of power to
augment normal electrical power load. One could use it during the lunar nite.
And for general emergency power needs.
And with beamed power one could establish a power grid in our solar system.
As with any grid or network, one, of course, starts by having two nodes, and then these are
expanded over time.

So you have electrical grid in space, which could have power generated in GEO, and the L-points- Earth Sun L-1 [which would have more solar radiation than in other location in the Earth/Moon system] Earth/Moon L-1 [could provide power lunar surface and for the production of rocket fuel from water], and other Earth system L-points could be places to generate power and relay power. With a few nodes in the Earth system, one could then expand them to Mars. Again, the Mars L-1 would get the most solar radiation available at Mars, Mars L-2 would also get more solar radiation than anywhere in Mars Low orbit or the Mars surface.
[It should noted that on average Mars gets 60% less solar radiation as compared to Earth. At Earth distance one gets 1400 W per sq meter and average at Mars distance is about 600 W per sq meter.
But in a 24 hour period- 600 times 24, one has 14.4 kW per day. One the Earth surface some the best locations [best location in America] one get only 8 kW per day. So at Mars L-1 [or L-2] even though it gets 60% less radiation, it gets more than 150% of energy available on the Earth surface per day.]

So, before even starting to think about transporting power from Space to the Earth surface, you could have thousands of tons of rocket fuel being produced in space per year, you could have a space power grid which is going to GEO, Earth L-points, and Earth low orbit and extends to other planets such as Mars. You might be making solar panels on the Moon. You might be bringing NEOs to Earth orbit or mining them in their existing orbits. You probably would be mining iron on the Moon. And beamed power may be used in ion rockets and/or microwave rocket which use water as a propellent. And probably a lot of other things going on.

So, by say 2060 one might be building vast solar arrays in space, which have as one of their purposes of beaming power to the earth surface market- and say provide 1% of total global electrical power needs. And by say, 2080 provide most of the Earth's global electrical needs.