We (well, Europeans) explored the earth when it looked quite similar to space exploration today. Year-long journeys with very little chance of survival, and no idea what was waiting on the other side. We ended up making some amazing discoveries (the new worlds) that turned out to be of vast economical benefits. Who says space exploration can't be similar.
(Yes, there is a lot of controversy over colonialism that I won't get into here.)
I think the Polynesians would like a word. And the "vast economic benefits" are dubious given the total human cost of introducing new diseases into unprepared ecosystems and populations - plus the import of abundant New World silver provided coin for the financing of the long, devastating mercenary wars of the early modern period in Europe and disrupted and destabilized the economy of China.
But in any case, humans had pretty much covered the globe outside Antarctica by the time Columbus set sail, in environments that, harsh as they may be, still provided breathable air, drinkable water and food if you knew how to hunt/scavenge/grow it.
Let's hope someone with a similar view-point doesn't discover Earth, then! :D
Jokes aside, you are right, of course. We don't have to worry about environmental effects or native populations in the same way when dealing with off-World colonies on sterile worlds. That alone should provide some incentive for commercial exploitation of things like asteroids; at some point Earth will either run out of certain elements, or other factors will result in certain elements being more easily obtainable off-world.
It doesn't matter. The speed of light is too slow for anyone out there to get here in a reasonable amount of time. Even if the universe is densely populated with aliens more knowledgeable than us odds are none are close enough to establish useful communication. That is by the time they realize they know more than us and that knowledge arrives we probably will have discovered it in on our own. (that leaves room to have alien art on the wall but nothing else useful)
We can't see crap now. We need more, bigger, better - and most importantly - space-based telescopes to be able to image interesting objects in anything resembling fidelity. There's e.g. a bunch of exoplanets, or hell, even planets in our own system, that we could image from a distance, if we could put couple hundred tons worth of equipment in space. For the more ambitious future, there are papers showing that you could even use the Sun itself as a lens to shoot pictures of exoplanets comparable with quality to photos of Earth from early days of space exploration! So, if we want to see things and truly learn about them remotely, we still have to get much better at sending things to space.
Robotics still ain't good enough to make it work alone, we'll need manned missions to establish a manufacturing-based economy in cislunar space, if we want to get anything done this century. Risky, manned missions, that in time will yield good profits.
NASA has a whole page about it now. And here's a rather large paper (I remember reading a shorter version, but with the same pictures inside): https://arxiv.org/abs/2002.11871.
During much of the Earth exploration phase destinations in Asia had more food and money than Europe (also easier to survive a winter)... I don't see this ever being the case with Mars.
It's cheaper to ship materials to Low Earth Orbit from Mars, than it is to ship those same materials from earth. Can you imagine our current space industry (worth billions of dollars) could be operated from Mars? If there was a settlement on Mars, they could do it for approximately 2/3 of the (fuel) cost of doing it from Earth.
Of course, an industry established at a moon settlement could do it for even less. :-P (1/4)
(Yes, there is a lot of controversy over colonialism that I won't get into here.)