Observation and communication of too many things to mention by satellites in orbit around the Earth.For example, for weather forecasting and for positioning.
Launching and operating satellites is sometimes a fully commercial activity carried out by companies.So you could say that the exploitation of space has already begun.
Research in wavelengths blocked by the vapor barrier.
Infrared research, which requires extreme cooling, is often better done in space.
A telescope on the back of the moon would work well: no more interference from the Earth.Certainly for some frequencies for radio telescopes this would be ideal.
Gravity waves research, similar to LIGO, but with satellites that use lasers over much larger distances.This measures different frequencies than is possible on earth and could provide insight into the behaviour of super large black holes and even over processes just after the Big Bang.
In the future a telescope at a very large distance from the sun could see extremely far, by using the sun as gravity lens.Given the cost of the James Web telescope, it might be useful to wait a few more times with a project that should be way and large.
In theory it is possible to make other materials in micro gravity.This could be useful for e.g. medications.
At the moment, however, as far as I know, there are still no things we need and really cannot be done on Earth.
It is theoretically possible to place solar panels in space and to send their energy as radio radiation to a point on earth.Also, mirrors could be used to get extra light on solar panels on Earth. However, these are not yet cost-effective methods.
Not everyone likes the same things.Space research can be useful in other areas and attracts very passionate researchers.
It will probably take hundreds of years to find a permanent, self-sustaining habitation outside the Earth.If something really bad happens on the earth, there is always a second chance.
As production and population on Earth continues to grow, there comes a time when the industry produces so much heat that it becomes a problem.That would make the current climate problems seem to be child’s play.
Probably then the only solution to move a part of the production to space.
There could also be shortages of certain materials, which can then be extracted from another planet or asteroid.
Actually, there can be quite a lot of people on the Earth.If the oceans and Arctic circles are used, they might be ten times as much. But if the population continues to grow, then an alternative to the space is very convenient.
In my opinion, we can, in this moment, mainly learn a lot of things that we can do in space.Exploitation of materials in space is going to take quite a long time.