Modern healthcare has extremely wide cost variability and long tail.
So any of us can have an accident or illness tomorrow that will require an operation that will cost €400k. Or €4k. Or €4m.
Most countries in the world, USSR among the first to be fair, introduced public healthcare, which is the only way to fund that really without effectively letting people die.
The cost is spread across the whole society, those who are young and healthy pay for those who aren't so lucky.