It's hard work because there are (at least) two subjects being argued, and conflation of the two is, at best, awkward. The point that people, whatever their mode of transport is, should be patient, tolerant and accommodating instead of impatient, intolerant and selfish is a metaphor for life, unarguable (and, in view of human nature, hopeless!). The other point that cyclists are not responsible for the vast majority of deaths and injuries on the road, no matter how stupid some are, is also unarguable. So to make an argument between those two points is futile. It doesn't follow that lack of responsibility for carnage implies that it's undesirable to be polite, but it's of limited relevance to the most salient point: cyclists do not kill or maim others, on the whole. But neither do the vast majority of drivers. So to take issue with any entire group because of the actions of some both misses the points that none of us is responsible for the actions of others, and that generalisations are often unhelpful.