Not all low-income individuals will qualify for Medicaid.
Someone can be low-income, but may still make too much money to get approved for Medicaid. Furthermore, only some states expanded Medicaid under the ACA. This means that some states require an even lower-income than others to become eligible.
When they are older and showing signs of dementia, usually a family member responsible for care will enforce the time limits.
Ability to evaluate a proposal's value and justify further investment.