This is a discredited faux definition from Robert Kiyosaki. The true definition of an asset is that it's anything of current or potential value.

You can see more here: https://themakingofamillionaire.com/wow-did-i-only-think-i-know-assets-vs-liabilities-94663a869e91

Or read the following from Investopedia (https://www.investopedia.com/terms/a/asset.asp):

"What Is Considered an Asset?

An asset can be anything that provides a current or potential future economic benefit to whoever possesses or controls that asset. Simply put, an asset is something of value that you own or that is owed to you. If you lend money to someone, that loan is also an asset because you are due that amount. For the person who owes the money, the loan is a liability."