After a 30% drop in units sold (Independent data from IDC 1), Apple revenue was only hit by 5% in revenue 2.

1 https://www.macrumors.com/2019/04/30/apple-36-million-iphone...

2 https://www.apple.com/newsroom/2019/04/apple-reports-second-...

And that's why they are trying to diversify revenue...