In simple terms we as a country every year are spending more than we make, our current national debt is about equal to our GDP ( our national income). As the economy contracts that will make our debt a multiple of GDP and it will become very difficult and more expensive to borrow money particularly as other countries will be in a similar position and it will be a scarce resource. Like other countries before us (e.g. Greece) any loans we can get will have conditions attached and a plan to reduce this debt. i.e. by reducing public spending and increasing tax revenues from a depleted workforce.
We are told that this crash could be worse than the 1930s. Back then benefits had to be reduced because of the increase in numbers claiming and the reduction in government income to pay them. So again in simple numbers, because I appreciate that many have never studied economics, if you can imagine that at the moment the total benefits paid was say £1,000,000 and it has to be shared between 100,000 people then imagine the impact of reducing that to £500,000 that has to be shared amongst 250,000 people. Instead of receiving £10 each, income is down to £2 each.
Only countries with strong economies can afford a welfare state. So when economists talk about the long term economic costs they are not being dismissive of the loss of lives now, but they know that the long term losses in a huge depression will be far greater.