Monopoly easialy beatable with few changes that probably won't ever be seen there though. How monopoly works in ToP? Basically top guild take all of the resources all by itself, and the rest of the playes can't fight them, because they getting stronger and stronger. in context of original top this include, but not limited to:
1)CA set, very powerfull equipment, especially at the start of the server, and incredibly overpowered if the voy with the most CA points wear the full set.
Additionally, you have no other way of getting it outside of CA.
2)UG - The only reliable in game source is CA again, I know some people successfully did craft those but the time it took was simply insane.
3)65 unseals/Kals - That is a bit harder to monopoly, but it sure is the issure as well. You need 5 kals to unseal equipment or to get boss stone equipment. You can actually craft those, but again extremely inefficient.
4)Black dragon. One of the most ugly and hardest to counter way to monopoly the server. BD gems are extremely powerfull, so is equipment, and so is 10m you getting, Don't forget how much 10m actually is in a context of a 1x rates server.
So what would be the best way to counter it? To add some harder, more time consuming(compare to pvp) ways to get stronger in pve, where you can't be killed by stronger people. While crafting already exist, it is not efficient enough, since it will require crazy igridients that will force you to grind stupid commerce quests or farming reputation. Not to mention, how much time it takes to level up instruments and find a good blueprint. So one way would be to add new methods or improve crafting, another would be to nerf PVP loot more, but that would be kinda cruel.
To those who think that PKO/TOP was fine the way it was, don't forget that there were few factors back then, that probably won't exist there.
First are hard mallers, who actually did contribute to economy a lot. They did sell fairy food/fruits/gems just to convert it into in game gold, not only it was possible to maintain your pet from that, you could even get some gems.
Second, inexpirience at start of the game, people did not know exploints and strategies they know today, it took a long time before first black dragon did fall, and the playerbase was so large, that even gemless guilds could do something with numbers. It sure would still be possible there, but the guilds acting differently a bit, if a guild who does the monopoly start losing, they simply recruit more people and that's the end of it.
Third, there are enough of good games to keep people from taking this game super serous, so if something goes completly wrong, they won't turn to crafting, they will just quit.