> Visa does[n't] need to hold the balance of my account.
Yes they do?
> Visa does[n't] need to or makes available all of my equity worth of assets for me to transfer.
This is a horrifying bug, right? A thing that no person would ever want, and it's so rare that visa would make you talk to a person and raise your limit first, or they'd get more people involved to make sure you're not being coerced because it's such an abnormal thing to do. Lawyers in some cases, just because you're being so silly. But if you REALLY wanted to make a $1b debit card transaction, you probably totally could, just call the visa billionaire line.
> Visa does not custody my assets.
But a regular bank can, and visa will send to and from there with a debit card.