I'm not sure personally. I've never heard a student with that lack of commitment last more than 2 years.
I have friends with that type of committment who have outlasted many burning enthusiasts, one has trained like that for many years, because of family, work and a long drive to training, and I admire him for that. Another one has had three kids and I admire her even more.
So unless you have been there yourself for a long time, I think it's risky to say others "lack" committment.
By that I dont mean to say one gets far with once a week, but if that is their committment, it covers the ground they stand on. I have learned not to judge committment until a person has been around for at least ten years. Probably more would make sense.