The crisis in the global economy, and the current collapse, began with President Bill Clinton's deregulation of the banks, creating an economy that has been progressively more out of control every decade since then.
The core problem is that banks are now allowed to create endlessly expanding 'money' in the form of loans and other private debt, including very esoteric instruments like 'derivatives' and debt 'packages' that have no basis or backing in real funds or assets on bank balance sheets at all.
Because of this ability, whenever there is a major market downturn the private banks and central banks (which are also private banks) use these mechanisms (and also lowering interest rates) to pump even more completely fake money into the system to prop it up, even though it just makes the underlying crisis far worse when they do this. The bank bailout following the 2008 crisis was upwards of 21 trillion dollars in such empty imaginary 'money'. This problem has become so out-of-control, that globally the total amount of this fake money, in the form of worthless debts and derivatives, has expanded to over 1 quadrillion dollars - yes, that's with a Q...
Think of the economy as a big balloon, with the banks pumping air into the balloon to further expand it (especially when it starts deflating). The banks are claiming that this increases the rubber in the balloon, when actually all it is doing is increasing air. Each time the banks have done this, it has made the balloon larger (but no more valuable) and at the same time has stretched the balloon so badly, that it weakens the balloon more and more over time.
So to bring the analogy back to the real world, everyone feels like the stock market and economy are becoming progressively bigger and stronger when actually they are becoming weaker and weaker, and so massive that they are extremely vulnerable to a progressively bigger and bigger collapse threat (in which the balloon will violently burst, thereby ruining lives all over the planet).
And that is exactly what just happened.
The actual cause of the global crash last week was not the virus, it was the ongoing failure of the Overnight lending market (also known as the 'Repo' market) which is a debt resolution market used every night to assure and balance the debts and credits of global economic activity so that all banks remain stable and solvent. Doing this is especially important when the economy has become such a fake blown up balloon as described above. If the Repo market fails with the global economy in that condition, disaster happens. And the biggest private banks play a big role in making sure that all of this precarious balancing will work out properly.
But last September, one or more of those big banks (probably JP Morgan Chase) faced an internal solvency crisis (and/or decided that the risk of buying debt in the Repo market was too high) and it backed out. This sent the interest rate for borrowing in that market from around 2% to over 10% and caused everyone else to start backing out (a situation which would have crashed the global economy had it continued).
At that point the US Federal Reserve stepped in to pump hundreds of billions of dollars of fake worthless 'money' into the Repo market intending to temporarily bail it out. But the problem kept occurring and the Federal Reserve then simply continued to pump trillions of dollars into the Repo market on an ongoing basis to keep it from failing (pumping the already strained balloon up even bigger and more dangerously). And the more this bogus money got pumped in, the more risky overnight lending became, due to the fact that there was no longer enough real value backing the lending market - and this simply perpetuated the worsening of the problem.
Once this was the global state of affairs, all it was going to take to cause a massive global economic collapse was a real world trigger that widely undermined the value of real goods and services in the economy. In 2008, that trigger was widespread mortgage debt failure. This time, the trigger was the coronavirus.
The virus is a big nasty pin, that just popped the balloon.