Of course weak password is bad. However, the major problem is not easy to fix.
More and more criminals are trying to attack data centers that have important user information and use that to unlawfully take your money.
Do a Google search and find a number of the big banks in the USA and overseas have had data loss. Data loss can be a polite way to say that data was stolen from the bank. So far, the banks and governments have helped resolve the trouble. But too often the criminals do not get apprehended and they go on to try again and again.
What can you do? Be careful about having large amounts of money in just one institution. Avoid credit cards that can be used to drain all the money from your cheeking account.
Some people now prefer to buy a plastic card for a given amount and use it to pay on-line bills or to go shopping. This is safer t than having your checkbook or cash in your purse.
The limited funds plastic cards are not linked to your bank and therefore a thief would only get the value of the card and nothing more. The card does not even have your name on it.