When a medical emergency reaches seven figures, a $10,000 deductible may be only the beginning of a household’s financial exposure. Mark Cuban is warning that the more alarming problem can emerge if the insurer refuses to pay a major claim at all.

The billionaire Cost Plus Drugs cofounder recently questioned whether people considering health plans with high deductibles are truly protected when an insurer denies an enormous claim.

“So I went down the rabbit hole of trying to determine what are the economics for someone, who is currently healthy, to go to a HDHP with a 10k plus deductible,” Cuban said on X in October.

“The question I asked is ‘I don’t trust insurance companies,” he posted. “What happens if I have a million dollar emergency and they won’t pay’ All I can say is WTF.”

A health plan with a high deductible requires the patient to cover more of the initial medical costs before the insurer begins paying a larger share of covered expenses. For someone who is healthy, that can still mean facing thousands of dollars in bills before insurance shoulders much of the cost.

Cuban’s central concern was not limited to the size of the deductible. He focused on what could happen if an insurance company rejected a major claim altogether, leaving the patient to dispute a bill far larger than the deductible.

His research led him to independent review organizations, which can examine certain disputed insurance decisions. Those organizations can become important when a patient challenges an insurer’s denial.

One company that surfaced during Cuban’s research was ExamWorks. Cuban recognized the company from a previous case involving a patient he had been trying to help.

Cuban then raised questions about whether the review system could create a conflict. His concern centered on companies involved in reviewing insurance claim denials while also counting major insurance companies among their customers.

“The biggest customers of the companies that are the final decision makers for insurance carrier denials, are the biggest insurance companies,” Cuban wrote.

He also questioned how state insurance commissioners oversee that arrangement. The issue, as Cuban presented it, reaches beyond what patients pay before coverage begins and into who ultimately decides whether a disputed claim will be paid.

His conclusion was a blunt warning for people considering these plans. “If you are looking at a HDHP, BE CAREFUL. It might just be rigged against you,” he wrote.

The concern could affect a substantial share of American workers. In 2025, 33% of workers with employer sponsored health coverage were enrolled in a high deductible plan paired with a savings option, according to KFF.

Among those workers, 35% had a deductible of at least $3,000 for single coverage. Plans carrying deductibles of $10,000 or more can place even greater pressure on household savings when significant medical expenses arrive.

The deductible also is not necessarily the maximum amount a patient could owe. Depending on the plan, patients may face coinsurance and other shared expenses before reaching the annual limit on what they pay from their own funds.

Those costs make the size of an emergency fund especially important when comparing plans. Premiums, deductibles, annual payment limits, health savings account opportunities and available emergency savings can all influence how much money remains for retirement, investments and other financial goals.

Cuban’s warning was not necessarily an argument against every health plan with a high deductible. Instead, it called attention to the deductible as only one part of a much larger calculation involving coverage, savings and the possibility of a denied claim.

For consumers weighing those tradeoffs, the most consequential question may arise only when the medical bill dramatically exceeds the deductible. Cuban’s warning focuses on that moment, when a household expects insurance protection but the company responsible for paying says no.