Steven Lopez has gone without health insurance for 15 years, and the Affordable Care Act hasn't changed his mind. Once again this year, he will forgo coverage, he said, even though it means another tax penalty.

Last tax season, the 51-year-old information technology professional and his family paid a mandatory penalty of nearly $1,000, he said. That's because they found it preferable to the $400 to $500 monthly cost of an Obamacare health plan.

"I'm paying $6,000 to have the privilege of then paying another $5,000 [in deductibles]," said Lopez, who lives in Downey, California, a suburb of Los Angeles. "It's baloney — not worth it."

While millions of people have gained coverage through the Affordable Care Act, an estimated 28 million Americans remain uninsured. And preliminary data shows that about 5.6 million paid a tax penalty rather than buy health insurance in 2015, according to The New York Times.

Now the future of Obamacare is uncertain. President-elect Donald Trump has made clear that the dismantling of the ACA will be one of his top priorities as soon as he takes office.

Some resisters like Lopez are feeling vindicated and other consumers simply don't see the need to sign up. Still others, according to Affordable Care Act advocates, are eager to take advantage of what will likely be at least one more year of subsidized coverage.

Doreena Wong, a project director at the Los Angeles-based nonprofit Asian Americans Advancing Justice, said consumers have already begun to express doubts on whether they should bother enrolling. That is despite redoubled efforts in recent days by the state and federal exchanges to encourage signups.

"Some people may ask: If it's going to be dismantled, why sign up?," she said.

Related: Rising Obamacare premiums anger those paying full price

Weiyu Zhang, a health educator and enrollment counselor with Asian Americans Advancing Justice, has enrolled 10 people since the election, which is about average for the beginning of the enrollment season, she said.

"Every single one has brought up the election and has expressed concern about signing up," Zhang said. People are asking whether subsidies might go away and whether premiums will rise or fall, Zhang said.

"What we know is that changes will not happen immediately, and if they want coverage in 2017, they should sign up," Zhang said.

Getting rid of the ACA in its entirety on day one of the Trump administration is practically impossible, said Erin Trish, an assistant research professor in public policy at the University of Southern California. Although Republicans to date have offered no official replacement plan, what's expected is a different approach with a less regulated health insurance market, Trish said.

She said the election's effect on this year's open enrollment period, which ends January 31, could go either way. Rather than opting out, many people might consider it important to get covered in case the ACA replacement options hinge on whether people had coverage in place, Trish said.

According to the U.S. Department of Health and Human Services, more than 100,000 people signed up for coverage the day after the election. In the first 12 days of open enrollment, one million people had selected plans on Healthcare.gov, the federal exchange website. That number was up 53,000 from the same period last year, according to the agency.

Related: Obamacare enrollment projected to grow 9% in 2017

Lopez said repealing Obamacare is fine with him. Being penalized for not being insured is absurd, he said.

"The government should not be in the business of forcing us to buy anything," he said.

Yet, Lopez does believe that covering those with preexisting conditions is a good thing.

So what happens if Lopez becomes ill? He must pay out of pocket.

Last year, he needed a colonoscopy. The best price he found was at a community clinic, where the procedure alone would cost him $2,000.

Not satisfied with the price, he traveled south to Tijuana. There, $2,000 covered a lot more: the colonoscopy, an electrocardiogram and hemorrhoid surgery, which he had been putting off because of cost.

If necessary, he'd do it again, he said.

For most Americans, cost continues to be the top barrier to health coverage. In 2015, 46% of uninsured adults of varying ages, ethnicities and income levels said they didn't have coverage because it was too expensive, according to a Kaiser Family Foundation survey. (Kaiser Health News is an editorially independent program of the Kaiser Family Foundation.)

Kathy Eller, 56, a janitor from Paducah, Kentucky, hasn't had insurance for more than a decade, and she plans to opt out this year as well, she said. Sometimes she worries about her health, but not enough to pay a $250 monthly premium, which is what the most affordable Obamacare plan would cost her, she said.

"I smoke way too much and I'm overweight," Eller said. "I go to the doctor once every six months for my high blood pressure medication and only pay $50 for it."

Before she lost her employer-based coverage 10 years ago, Eller underwent several surgeries for a skin infection caused by a bacteria known as MRSA.

Related: Frustration runs deep for customers forced to change Obamacare plans routinely

If she were to get severely ill again, she wouldn't be able to pay for it, and she doesn't think she'd seek treatment.

"The way I see it, I'm 56, and my family doesn't live very long — into their 60s, maybe 70s," she said. "I wouldn't want to put that financial burden on my husband, he doesn't need that."

Last tax season, Eller was fined close to $800 for not having health insurance. Eller said she is indifferent to the possible repeal of Obamacare. "It hasn't helped me much, but I know it's helped a lot of people," she said.

Shannon Drees, 26, a student from Orlando, Florida, hopes possible reversal of the ACA could lower premiums for young, healthy people. She has not had health insurance since she was 21, when she was dropped from her parents' plan before the ACA provision allowing young adults to stay on those plans until age 26 took effect.

"I don't have outstanding health issues, it's much cheaper to pay a penalty," she said.

Last tax season, she was fined $500. That's still less expensive than the estimated yearly cost in premiums for plans she looked into, she said.

Many of her friends are in the same boat. Unless they are covered by an employer, they are not insured, she said. She said she does not visit the doctor much and uses Planned Parenthood for birth control.

"For me, it's about the math," Drees said. "Hopefully one day I'll be able to afford it again."

Kaiser Health News is national health policy news service that is part of the nonpartisan Henry J. Kaiser Family Foundation.