Investment bankers are often called ‘sharks’ and this is, in fact, a good description. There is nothing wrong with sharks: they are beautiful animals designed by billions of years of natural selection to do one thing extremely well. You can not expect a shark to be other than a shark: rather you must understand how sharks behave and arrange matters so as not to be eaten. Governments can do this for banks: they did it in 1933, after all, and it served us well for nearly 70 years. However governments entirely failed to do this after the events of 2008 for reasons of stupidity and corruption.
In 2016 their failure to act came home to roost: the housing bubble in the UK collapsed causing a cascade failure of investment and retail banks. Initially this was confined to the UK but it rapidly spread to the US. The retail banking system held together for a while after its forced nationalisation, but decades of IT mismanagement combined with the exodus of staff, mostly to China and South America, led to its final collapse in early 2017. Starvation began in the US in February: in the UK food shortages, already serious, became acute in May of that year. After May it becomes hard to disentangle events: we know that the US launched a strike against the Russian federation in June to acquire grain, and that there was a limited exchange of nuclear weapons. The most serious result of this was the effective destruction of the internet and telephone networks as a result of EMP and the resulting loss of almost all communication and reliable records. The US also launched an attack on Canada, once again for grain, to which the UK responded, ostensibly to defend a Commonwealth country but probably in fact to secure Canadian grain stocks for itself. The resulting nuclear exchange destroyed London and most of the US east coast cities not destroyed by the earlier US-Russian exchange. Much more seriously the weather effects from these two exchanges of weapons caused the near-complete failure of the harvest in Canada and the northern parts of the US in 2017. Late in 2017 there was an attempted invasion of the UK and France by remaining US armed forces: this was repulsed with a further exchange of nuclear weapons. This is often known as ‘the second American war’ and also as ‘the fall of France’: before this time France, as the only country with an energy strategy not dependent on oil (which had become scarce after the Russians nuked most of the Middle East in the earlier Russian-US war), was relatively stable, but the US specifically targeted French nuclear plants in the second war, leading to the failure of French infrastructure. By the end of 2017 over two hundred million US citizens had starved and there was no effective government in the US, Canada, the UK, France, or Russia.
Things got a lot worse later, of course.