If you do not have a spouse, partner, or relative who is prepared to make an application to the Court to become your court-appointed guardian, and an assessor has issued a certificate of incapacity, the government (Public Guardian and Trustee) will become your guardian over your property or personal care or both, depending on the circumstances.
The only way to avoid this is to have Powers of Attorney properly prepared and duly executed while you are in good health and can take the time to make the right decisions.