That’s not quite how economy works. When prices go up, fewer people buy, because some cannot afford it or will decide they have other priorities. There are whole Ph.D. theses around how to find the sweet spot that maximizes profit.
You’re also ignoring DMT runs are not a limited resource and the moment you make DMT more profitable you attract more players that could do it today but don’t bother yet because they don’t find it worth it. Your “massive competition” will necessary get worse.
Other practical problems:
- You need to contact everyone doing tributes for gold. You’re not reaching a lot of people in these forums (let alone from your realm).
- Everyone must agree to apply the same prices (which may not be exactly your proposal)
- When two or more “tribute runners” are available at the same time they must organize themselves to split their clientele or profit
- Everybody must resist the temptation of offering lower rates to attract a larger part of the cake, even if that means going home empty-handed after clearing DMT if nobody accepts their prices at the moment they offer their services.
- Large guilds often do their own DMT runs for buffs and gear and even sell it once done. Making DMTs significatively more expensive will attract even more guild runs.
A cartel this big is virtually impossible.