Interesting how you linked to feivel’s post, which brings up a point which hasn’t been brought up yet but should be: not call kollel men are cut from the same cloth. When discussing these issues, it needs to be clear about whom we are talking – the less serious, short term learners, or more serious l, longer term learners. Those two factors are heavily correlated, especially inasmuch as it’s not the norm (though it exists) that someone who is not being productive sticks it out for many years.
Hence, feivel describes wonderfully dedicated kollel men with large families, which means they’re long term learners.
The less serious, dedicated ones don’t usually stay until they have large families.