Whatever you want to call it, it's obviously taking someone else's rightfully owned property without their permission. They (or someone who gave it to them willingly) have produced something of value and earned that wealth. To take it is wrong-- lawful or not.
The great German sociologist Franz Oppenheimer pointed out that there are two mutually exclusive ways of acquiring wealth; one, the above way of production and exchange, he called the "economic means." The other way is simpler in that it does not require productivity; it is the way of seizure of another's goods or services by the use of force and violence. This is the method of one-sided confiscation, of theft of the property of others. This is the method which Oppenheimer termed "the political means" to wealth. It should be clear that the peaceful use of reason and energy in production is the "natural" path for man: the means for his survival and prosperity on this earth. It should be equally clear that the coercive, exploitative means is contrary to natural law; it is parasitic, for instead of adding to production, it subtracts from it. The "political means" siphons production off to a parasitic and destructive individual or group; and this siphoning not only subtracts from the number producing, but also lowers the producer's incentive to produce beyond his own subsistence. In the long run, the robber destroys his own subsistence by dwindling or eliminating the source of his own supply. But not only that; even in the short-run, the predator is acting contrary to his own true nature as a man.
Nothing is more admirable than the fortitude with which millionaires tolerate the disadvantages of their wealth. -- Nero Wolfe