Yeah except probably not. Its not like billionaires have a savings account with $1,000,000,000 sitting there collecting 5% interest (much less sitting collecting even less interest in a checking account...)

They have a net worth based on tons of diverse (non-liquid) assets like securities, company ownership stakes, real estate, art, etc. To say nothing of their holdings in trusts and shell companies abroad, or whatever the latest tax avoidance strategies are.