What can I do to stop this?

[Brian_]

I don't really understand the concept of efficiency in leaving a dungeon and taking a 30min penalty, doesn't sound efficient to me at all.

Because if your goal is tomestones, there are faster, more efficient alternatives. First, the PvP queue and Dungeon queue run on separate penalties so even with the penalty from dropping out of a dungeon, you can still queue for PvP. Second, you can just do hunts or whatever daily tasks you would otherwise spend time doing.

So rather than spend that time laboring through a dungeon you don't want to do, you can spend it doing things you want to do or need to do.

You are confusing "selfishness" and "motivation".
The reason you are being selfish and the OP is not is that you are screwing other people over in pursuit of your goals.

And how is he not screwing me over for the pursuit of his own goals by wasting my time in a dungeon I don't want to do?