Do you think other poor people trying to start businesses don't try to do it with "almost no monetary investment"? Not only they try that, that's the only way they can afford to try anyway.
Still no match for a big monetary investment, and still much much harder for them to get the same outcomes as an enterpreneur coming from privilege. Notice also how the claim isn't that it's impossible (or inversely, that the rich always succeed to build a succesful business), but that it is much much harder, and the upper middle class/rich/connections people have it much easier.