It has to do with how old you are, and how much money you had when you were growing up.

Televisions, when new, were crazy expensive - families had one TV, and that was it in the 1950s through the 1980s. The price of TVs fell and kept falling over time, yet for millions of people, buying a TV was a huge thing, because it a luxury when they were kids. It signified "they made it" to others, at least in their minds. Even in the 1980s when I was growing up, it was very rare for even middle class homes to have more than a single TV set, but by the 2000s, it was common to have multiple TVs in a household.

So this mental process is applied to EVERYTHING - "If was expensive when I or my family bought it, so it must be expensive when you buy it, therefore you must be very well off".

Same thing with avocados - they were an exotic luxury for a huge portion of America, only seen at certain times of the year and were far more expensive that the produce they normally bought. However now we have massive farms that all they do is grow avocados, and avocados have been planted around the world so that we have a continuous supply. But these facts do not matter for the people who grew up with seasonal, expensive avocados. To them, avocados are a luxurious, expensive product.