Once upon a time, there was a chef who lived in a community of people who didn't know much about food. The people didn't know how to cook, and only had a vague awareness that there were different types of food available.

The people were perfectly satisfied to eat McRonald's, for every meal of every day.  The chef cringed every time he thought about this.  He understood — much better than anyone else — that McRonald's food is mediocre, over-priced, and unhealthy if eaten regularly.  When the chef expounded on the woefulness of the dietary situation, his friends would nod their heads in agreement — but with not much enthusiasm.  And while they understood his arguments in an intellectual sense, none of them felt particularly inclined to make any practical changes.

One day the chef had a grand vision: he would teach the people to appreciate finer food.  He would need to start by cooking for them, so that they could have some understanding and experience of fine food.  Then, as their interest increased (as undoubtedly it would) the people would be prepared to learn how to cook by themselves.  He would teach them, and eventually there would be a cultural change: the entire community would come to know the benefits of home cooking, and the stranglehold of McRonald's would be loosened.

At first, a number of the chef's friends were enthusiastic.  It was the chance to try something new (and to get some free food).  On trying the chef's food, many of them were intrigued by the experience of sampling dishes that were entirely unknown to them.  However, the overwhelming enthusiasm (and even joy) that the chef expected was tempered by the fact that — sadly — the people didn't have enough culinary experience to appreciate the chef's exquisite dishes.

If you do someone a favour for long enough, they come to expect it as a right.  And so it was not too long before there were some grumbles about the chef's food.  For some, a particular dish might be too bland, or too rich; other dishes might be too spicy, or might lack flavour.  And if the food were ever late, or a bit cold, then it was perceived that the chef had failed in his "duty".

The situation didn't improve over time.  The chef came to be blamed for certain woes experienced by the people.  Someone would occasionally eat a dish that was too rich, and so suffer a stomach upset.  The natural reaction was to blame the chef and his cooking: "This would never have happened, if I had just stuck to McRonald's".  Sometimes the blame was completely unfair and unreasonable: people had a vague understanding that there is a relationship between diet and health (quite ironically, this was partially due to the activism of the chef).  So when people suffered from the sorts of ailments and conditions common to all people — colds and 'flu, sprained ankles, premature hair loss, etc. — it was natural to question whether the chef's diet was somehow involved.

All of this was exasperating to the chef, who seemed not to understand that people are pre-disposed to form negative impressions of new things. Negative experiences cause negative impressions... except in respect of the ordinary.  When there are problems with the ordinary case (in this instance, McRonald's), people shrug their shoulders and accept that that is "the way things are".  Furthermore, people become selective in their observations: once a perception is formed that something is wrong, people will pay extra attention to any evidence that supports the idea.

Then one of the chef's friends made the mistake of suggesting to the chef that he might do well to make his food "a bit more like McRonald's".  The chef's first explosion of anger subsided into a more reasoned explanation of the relative merits of fine food... but the damage was already done.  The chef's friend felt aggrieved — after all, he was only "making an innocent suggestion" — and the chef gained a reputation for being arrogant and elitist.  The people murmured about how he was trying to "force" his "snobby" food onto them, and trying to manipulate their behaviour towards some shadowy objective.

Many of the people abandoned the experiment, and went back to McRonald's — and felt much better for it.  The chef became bitter about the "ignorance and stupidity" of his fellows, and thereafter there was a divide between him and them.  He had learned something, but unfortunately he did not draw the right conclusion: people won't change until they are ready.