Not everyone has health insurance, especially in the United States. Although the number of uninsured has dropped since the implementation of Affordable Care Act (ACA) which giving subsidies on healthcare plan, many Americans still choose not to apply or having healthcare plan. Many citizens are not qualified for healthcare subsidies, although many others are qualified, they opt to not participate in government healthcare plan. Moreover, some employers change their benefit program which cause financial difficulties for their employees. In the end, many people did not think health insurance as their needs. 

There are many reasons why they did not have health insurance, such as:

There is indeed a risk (or more) for not having health insurance. The obvious risk is financial difficulties once the uninsured need medical assistance with expensive cost. Another risks are unable to have some types of medical services and have to pay tax penalties.Having health coverage give advantage for people who want to access preventive care for free. Since ACA requires many preventive services to be covered in insurance policies. Preventives care is important to detect illness early before it can develop into critical problem. It also increases the success treatment probability. 

If you have no health insurance coverage, you need to pay your medical expenses with you own pocket. Sure you assume you will not require medical assistance for years, but what if you need to be hospitalized because of accident or sudden ill? The medical expenses is no joke. Having no health coverage can make you fall in debt or even bankruptcy. In addition, you will get tax penalty, assuming you relatively healthy. You might have to pay penalty as high as health insurance premium.