A time to stop contributing to Medisave

As long as one is employed, one continues to contribute to CPFMedisave for as long as one is alive. For self employed, they will have to continue contributing to Medisave even at 100 years or more under the present rules. What is the logic of contributing endlessly when CPF savings can be withdrawn progressively after 55?

The other point is the bottomless limit of Medisave Minimum Sum to be