Probably because they know that Obama will eventually pay for them.
Check it out:

The left-leaning journalism organization ProPublica says the only Obamacare deadline that matters is the one few are talking about: the recently extended January 10 deadline by which so-called Obamacare “enrollees” must make their first premium payment to officially activate their insurance plan.

No payment, no health coverage, notes ProPublica writer Charles Ornstein.

“There’s a huge caveat that isn’t getting much public attention,” says Ornstein. “For coverage to take effect on Jan. 1, enrollees must pay their first month’s premium on time.” Ornstein says this overlooked fact raises “the prospect that actual enrollment will be far lower than the figures HHS [Health and Human Services] is releasing.”
Industry consultant Robert Laszewski told Ornstein that one of the insurers he works with said just 15% of people have paid and activated their plan so far. Another consultant, Kip Piper, put the figure even lower.

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