How does Bill Gates make sure that some of his money is not stolen by banks or other entities who work for him?

Answer

Personally, I assert that Bill Gates can not save his money 100% from stealers and he was been stolen before

Konstantin Simeonov Kavrakov, a Bulgarian hacker, who hacked into the ATM and stole thousands of dollars from the bank account of Microsoft mogul Bill Gates with fake ATM cards arrested in Philippines, according to the Philippine National Police.[1]

In 2011, Kavrakov got arrested and was jailed in Paraguay for hacking into the Bill Gates' account in The Philippines' densely-populated Quezon City and stealing thousands of dollars. Since then Kavrakov was on the hit list of many countries police.[2]

Footnotes

[1] Hacker Who Stole Money From Bill Gates Arrested in Philippines

[2] Bulgarian Super Hacker Robs Bill Gates, Nabbed in Paraguay - Novinite.com - Sofia News Agency