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?

[Violette]

When you que for a roulette you open yourself up to the possibility of non-preferred dungeons.

Leaving a roulette because "I didn't want to do x/y/z dungeon" is like throwing a tantrum because you didn't get the Christmas present you wanted last year.

You're old enough to know things don't go your way and you should be ready to accept that, but you still didn't think about anyone else and ruined their time as well.

With tank que comes tank responsibility. You're the instance leader the moment you que as a tank and screwing nine other people because "ungh this dungeon takes to long to clear"is not something you can argue will ever be justified.

[winsock]

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?

If you dont want to do dungeons in the roulette, dont use the roulette. You're selfish because you're going into it knowing you have the possibly of not getting what you want, and screwing ppl over if you dont get your way.
In the OP's scenario, he is queuing for dungeons other ppl are also queuing for or that is contained in roulettes that ppl are queuing for.

In short, when you queue roulette, you consent to being available for any possible duty within that roulette. Crying and screwing over the rest of your party when you dont get the outcome you wanted from a "roulette" is childish and selfish.