Why would someone need to convince you. Eventually someone gains money and power, uses that money and power to kill you and take your land, which is used to further gain money and power. Over time, someone will challenge that person, wage war on the group in power, kill and depose them. And the cycle continues.
I'm sure you'll argue government does all those things (true - see the United States government), and in fact that band of thugs is just "government" by another name. And that's kind of the point, really. The alternative to no government isn't peace - never has been. In fact the alternative to no government isn't in fact no "government" just a different way to order society, or what you perceive of as better "government" which is presumably smaller than the existing forms of "government."
Just think of your land dispute. If someone with a band of thugs starts killing landowners and claiming he's the rightful owner, this non-government community will organize to prevent further improper takings, and/or take concrete steps to reverse previously improper takings. But what standard does it use to determine if that guy who killed your neighbor and seized the land was improper, versus him claiming land that was legitimately his and he is merely forcibly protecting HIS rights? Who knows, but what we do know is a standard has to be developed, and as it's enforced becomes the 'law' or its equivalent, because it's a uniform standard the community uses to mediate disputes. That is aka 'government.' It might be formal or informal. As a community grows, it will become more necessary to formalize those standards, versus the nearest 10 guys who are asked to help defend the landowner making up the rules with each request.
Maybe over time those 10 guys get a reputation for being reliable and fair, and when land disputes arise, the community comes to trust their judgment, and they become the equivalent of the local judges. Etc.....
Point is especially in modern society, if government didn't exist, we'd soon create something that looks exactly like "government" in its place, because we must. Randall promises to do a job Mary $1,000. After it's done Mary refuses to pay, arguing Randall messed up the job and so she's not going to pay but $500. You might say, well, if Randall did a bad job, eventually people will quit hiring him! Or, alternatively, soon enough Mary can't get anyone to work for her because she doesn't pay her bills. But how do we know who was in the right in that dispute between Randall and Mary? That's actually VALUABLE information in a community. Who should they trust? Mary OR Randall? If it's Mary, the community should get together and refuse work for her unless paid up front. If Randall, quit hiring him because he's a liar and incompetent. That MATTERS! It would help whoever helps resolve this dispute if Randall and Mary agreed to what the job was and the standards and we have....contracts!! But who looks at the contract and then says, 'Sorry Randall, but you didn't do what you promised. Mary was correct!' Well, trusted members of the community will do that....aka judges, government. Etc. We could do examples all day.
