On what basis is anybody predicting a second wave which gets worse? This seems completely backwards from everything we know.

The Spanish Flu accidentally had an inverted forcing function--we sent the worst cases back to their home countries which helped spread the most severe cases rather than the mildest.

For Covid-19, the cases most likely to spread are going to be the mildest. The worse you feel, the more likely you will pull yourself out of circulation. And, if you are obviously unwell, people are going to force you home.