boycotts against israel follow the same logic as strike-related boycotts: organised action toward a material goal. it is not about performing any kind of moral purity (except to the degree that it entails signalling political values to others*), nor is it about divesting yourself of any kind of guilt. the goal is to provide support to on-the-ground struggles in palestine by applying outside pressure. if there were no concrete action being taken in palestine and israel, bds would be pointless. but it was literally founded by palestinians. the boycott is being called for by palestinians.
"there is no ethical consumption under capitalism" is a cynical and worthless argument against bds.
* yes i am saying bds involves virtue signalling and it is in fact a good thing