I believe every country has a reasonable threshold for a balanced account to avoid arousing suspicion from local financial regulatory bodies. Banks may inquire about your occupation and estimate your income, but if the assets disclosed exceed $10 million, I believe it would draw the attention of the IRS.

Gradual withdrawals are a simpler way to steer clear of scrutiny. If you're earning your money legitimately, I think you should be able to explain it well, and there shouldn't be any grounds for legal repercussions during an audit.