"Damn it, I'm taking it! Worst comes to worst, I'll just live like a parasite from now on!"
The so-called instance parasites are those with a certain level of ability who don't want to continue participating in new instances.
They typically choose a few familiar instances, deliberately suppress their own strength, and keep alternating between these familiar instances, each time trying to clear with the lowest possible rating, meeting the minimum instance requirement once a month.
There are many such instances; as long as one is strong enough but does not attempt to complete the instance task, one can enter this very safe infinite loop.
The only drawback is that entering a specific instance consumes a registration card, which is why the supply of registration cards is plentiful but prices haven't dropped.