CPF is ultimately meant for retirement, and to ensure that the future generations are not overly taxed with the burden of supporting the elderly. It isn’t meant to be your personal bank account where you can withdraw funds as and when you want. If you choose to use cpf savings for your housing, the condition is that you are able to sufficiently provide for yourself and would be able to cough up the amount plus interest to support your own retirement. If you accept that you are always free to NOT use your cpf funds for housing, or just don’t sell your house.