This isn't a knock-out game, go guns blazing. If you don't overcome your weakness of chasing right now, what will happen in knock-out phase where it'll be do or die? You can't expect to always win the toss and decide to bat first.
First of all, Bavuma needs to go. There are more deserving players out there and the South African selectors can't select him as the opener everytime just because he is black. He is not only underperforming himself, but also dragging down the entire team with him. Anyway, it is almost confirmed that they will finish either at the 2nd or the 3rd position in the points table. Therefore they will avoid facing India in the semis. But even then, they need to formulize a strategy against the possible opposition (Australia / New Zealand / Pakistan).