I used to work in the City at the coalface of the global finance industry but agree with the sentiment which underlies your comment. The global finance industry is almost ungovernable in parts and has done great harm to a lot of people. However, the argument needs taking apart a bit.
First up it depends on what you mean by 'banks'.
The basic high street banking services of clearing and settling payment transactions is essential to our modern economy and poses no risk or harm to anyone. It needs speeding up and making more efficient but we al depend on it.
Then there is deposit taking and lending to domestic businesses and households. Here there was far to much lax lending encouraged and endorsed by Bank of England and despite the financial crisis the Bank of England is pulling out all the stops with zero interest rates to get us and businesses to borrow like crazy again. This is wrong. An economy built on excessive debt and house price inflation is totally unsustainable. This needs curtailing.
Then we come the large international money centre banks who do a lot of basic banking for international business, foreign exchange, trade finance, letters of credit, leasing on capital equipment, project finance, mortgages on office buildings, commercial paper lending and helping large corporations raise finance in the global money markets. This again is essential and with the backing of good security and prudent lending poses no risks and is essential to the global economy.
Finally we come to the investment banking industry and all the complex derivative and speculative financial market activity. Essentially trading highly complex financial instruments are investments mainly for short term gain with huge amounts of borrowed money provide dby the world's central banks at exceptionally low interest rates has driven global financial markets to unsustainably high levels again with a bubble inmany places that will burst with dire consequences. This is what poses a massive risk to the global economy and this risk has actually increased since the financial crisis. Indeed it is so out of control that worlds central banks (eg Bank of England and Federal Reserve and ECB and Bank of Japan and Bank of International Settlements dare not curtail its activities (eg by withdrawing quantitative easing or raising interest rates or raising capital requirements) without casing another financial crisis.