Gen. 12:6--The Canaanites were then in the land
Gen. 13:7--The Canaanites and Perizzites were then dwelling in the land
When Avraham Avinu is sent on his first sojourn, the Torah reports--pace Rashi on 12:6--that the Cannanites were in the process of conquering the local area from the children of Shem, to whom the land was granted after the Flood.
When he returns from his short Egyptian tour, and his sheperd have a territorial rift with Lot's sheperds, the Torah uses a slightly different turn of phrase, as if to say the conquest was at least de facto recognized.
This set of circumstances may or may not be in conflict withthe very first Rashi in the Torah, where the idea that the land of Canaan somehow "belonged" to the Canaanites before we "took" it, but that said appropriation was Divinely justified.
(Aside from the Rashi/Midrashim, "Canaan" is oft used in contemporary times as a pedagogical and political paradigm; pedagogical: to paraphrase Rav Zev Leff, it's no accident that Jews, the ultimate slaves to G-d, are given the land frst given to Canaan, bearer of the curse of eternal servitude; and political, in that some enemies of the Jews from without and within have become enamored with the idea that there are modern "Canaanites" who are the true indigenous inhabitants of Israel, ignoring the fact that making use of the Torah to justify said claim simutaneously undermines it, as the Canaanites are identified as the original "occupiers". Like the argument of Geviha ben Pesisa (idenitifed as the "first Jewish lawyer") in Chelek (TB San. 91a): "You bring the Torah? I will also [beat] you with the Torah.")
Yet, Rashi also reports at 13:7 that when Lot's sheperds tried to use G-d's future promises to Avraham regarding the land and the fact that at the time Lot was Avraham's sole putative heir to justify their larcenous grazing as if the land was already theirs, the answer from Avraham's camp was "it isn't yours yet"; the actual historical fact of Abrahamic possesion was not yet established, even given the ab initio illegitimacy of the Canaanite conquest.
This might raise separate questions as to when legitimacy is de facto accorded to de jure misappropriation, but at any rate, the immedate result of this wooly imbroglio is that Avraham channels his inner Dylan in 13:9: "you go your way, I go mine", and Lot departs, muttering sotto voce "I want neither Abram nor his God". The Abrahamic ideal was "tried" by Lot and his sheperds in a rather narcissistic and disngenuous manner--using prophecy/religion to justify theft--and subsequently found wanting and left truly untried: Lot walks away from the the entire enterprise. (Interestingly, Avraham Avinu, the mekarev par excellence of his time, didn't impose further: at this point he lets Lot choose his own derech, likely realizing from this incident that any pretentions to piety on Lot's part are ultimately self-serving.)
Lot and his minions also have being saying that it was a "mitzvah to steal from the goyim". This mindset might present itself in contemporary times as either the gross misconception that stealing outside the tribe is ever sanctioned, or that appropriation of disputed private promontories outside proper channels is somehow meritorious. It's possible that the near-repetition of "Canaanites in the land" might be a hint that this kind of behavior in fact resembles a "ma'aseh eretz Canaan", underscored by the medrash where Canaan tells his children to "love theft" (TB Pesachim 113b).
The contemporary takeaways might be the following: one, never use religion or nationalism as a basis to justify purely personal ends--"the personal is political" as a prescriptive is an anything but Jewish philosophy; two, this has no bearing on proper attitudes towards those who wish us harm because we are Jewish: there are proper religious and extra-religious channels through which they can be dealt with, and none of them have to nor ever should involve misappropriation or personal-level harrassment (or worse); third--and this is a longer, more involved discussion--one might be able to distinguish between an individual as ostensible bigot (because minds can be changed, although in a day and age where evil designs more often than not may be expressed in semi-public digital fora, all declared Judeomisics bear watching) and a Judeomisic public figure cashing in on antisemitism, where public opprobrium is only the first among legitimate options in countering the danger.
But you still don't take their stuff.
