Okay, follow my reasoning:
The stock market is like a big water tank with two pipes, one in and one out. The 'in' is the flow of money being invested, and the out is the flow of money being withdrawn. If the amount going in is greater than the amount going out, the indexes will rise (on average; I know it's made up of many individual companies etc.). If the amount going out is greater, they will fall.
While we like to think about what retail traders are doing (because that's what we are, mostly), the main inflows are actually coming from institutions like big banks and pension funds. The main outflows are, again, big banks and pension funds. Specifically, inflows from retirement fund and pension contributions, outflows from pension payments and retirement fund withdrawals.
During this crisis, the inflows are likely to be greatly curtailed as people go without work, while the outflows will mostly remain. So no matter how much you want to "buy the dip," and no matter how sound that advice is, the scale of the effect is dwarfed by the gap in inflows.
Am I wrong? Am I stupid? I'm not basing this on anything I read, just kind of spitballing.