If you run a pub, either you're tougher than any challengers or you employ bouncers. Maybe you even have the local community on your side because they like how you run the pub.
The problem is if someone amasses enough capital to pay a gang of thugs to do his bidding. Then you can just take over properties, which earn you more money to pay more thugs. You can easily scale that to a global organisation. That's basically what drug cartels are. They run just fine, trade with other illegal organisations etc. It's just that the overhead of building infrastructure and providing security is enormous, so it only really works in extemely high margin industries like illegal drugs.
But according to anarchist theory, those thugs wouldn't do that because that would violate anarchy. This is the problem with most political theories. They assume near 100% compliance.
The problem is if someone amasses enough capital to pay a gang of thugs to do his bidding. Then you can just take over properties, which earn you more money to pay more thugs. You can easily scale that to a global organisation. That's basically what drug cartels are. They run just fine, trade with other illegal organisations etc. It's just that the overhead of building infrastructure and providing security is enormous, so it only really works in extemely high margin industries like illegal drugs.