The DA may be arrogant. The ANC have been arrogant since 1994. Their arrogance was only shaken by the weakness of Zuma which caused alarming division in their ranks.
Why are the IFP, UDM, Cope, ACDP and FF+ not arrogant? Because they are so insignificant that they cannot afford to be. In fact, they are divisive instruments in SA politics where their leaders found a way to become just relevant enough to get to the gravy regardless of being small.
If the DA is arrogant it is because they sense power, they have support and feel they are now more relevant than the ANC.
But they have one problem. The ANC may now be in difficulty, but it will only be until voting time. Then the old faithful and every Jack will leave all arguments and gather around the flag to once more vote the same old story into power which will perpetuate our economic malaise and stagnancy.