It might be my opinion and I'm different than others' in this forum, but
money is wealth. Real Wealth.
Do you consider gold wealth? Well, Gold is just a kind of material with high demand. The same for money. The same for a car. It's just a set of materials linked together, and they work

Well, so money is real wealth. But like wealth (Gold or Silver), money don't get destroyed or banks don't destroy it. What happened is that banks were investing their money in various mediums like stocks, bonds, loans, investments... When the crisis happened and the value of these investment decreased, banks faced bankruptcy and many banks did go bankrupt.
So if you consider the bank and what it does as a wealth, then yes, it got destroyed by the crisis (that started for whatever reason).
But for this part of your post
People always say that financial crisis destroyed trillions dollar worth of wealth
All I can say is that people says lot of stupid/non-sense things.