Is there any reason for an economically prosperous nation to

the primary reasons france conquered Algeria the first time were

1. raw materials (this was by far the biggest one)
2. countering other empires to maintain the balance of power (imperialism was seen as a kind of arms race, especially due to its zero sum nature, if france didn't take algeria one of its rivals would)
3. nationalism (those poor savages would be so much better off in our enlightened empire, was mostly bullshit and very little was done to actually improve algeria but that was the justification)

none of those are really relevant today, algerian nationalism is far, FAR, stronger than it was in the 19th century, and the international community would not take such an act of agression lightly, so France really has nothing to gain by attempting to conquer Algeria.

It wouldn't make any sense.

Colonialism, on it's face, was about national pride and conquering the world, sure. But at it's heart, it was really about forcible globalization, getting access to much-needed geographical resources that weren't being utilized at all and putting them on the world market.

Consider China in the run up to the Opium Wars. They had a policy where they were willing to export things like tea and silk that the West wanted, but only in exchange for silver. Imports of any kind were not allowed. Sounds great for the Chinese, right? Except the inflow of silver into a closed economy outputting a static amount of goods each year just led to price increases. If the Chinese had traded their tea and silk for extra grain or industrial resources or something of tangible value produced in the West, they could have fed more of their people and switched over more of their farms to tea and silk production, benefiting everyone because Europeans would have a new market for special goods and wouldn't have to worry about going bankrupt from their tea and silk addiction. But they were stuck with an unenlightened mentality, and the Europeans had to blow the doors open by smuggling in opium to get their silver back.

Nowadays, countries tend to understand this. If there's a bauxite deposit in the Central African Republic that a Western company wants to mine, they can fly there, cut a deal, and nobody will stand in their way. Back in the olden days, they would have had to trek through Africa and then been attacked by tribal spearmen who thought they were evil spirits

Yes, say that Poorland got a lot of crystalline water and Richstein needs it. By Richstein I mean, of course, the rich that run the whole country.
First, they just go there, set shop, trade their dragon dildos for water, turn the water into ULTRA water, and sell it to the whole fucking world at 100000% the cost. That is the cheaper and most profitable way to achieve dominance.
Now, suppose that Poorland got some folks with money, and they decide that they want to make their own ULTRA water. The jews in Richstein get a bit scared of the competition, and try to drive Poorland entrepreneurs out of the market by underpricing stuff, making the wages too high, etc. That is more costly, but it still won't cost that much, and they are still profitable during the whole operation.
Still, some fucking self-made men from Poorland will thrive, and that is when the good people of Richstein get scared. At this point, the operation will no longer be profitable short term, because they will have to buy judges, senators, etc... to keep their advantages. They are betting that after they make sure that their monopoly is intact, the profits will justify the extra investment.
But some times, for a lot of random reasons, they won't be able to achieve the political power necessary to keep control. And after investing all that money, the next logical step is to invest a little more to convince the peasants in Richstein about how evil Poorland is and how they must take arms to fight for freedom, god or whatever. And that, my friend, is when it is logical for rich nations to invade shitholes.