Most companies have their prima-donna's but is there a scale of.... ?

Do you mean on rising prima-donnas

Do all ac techs aspire to be industrial engineers

The ones I know just want to be working less hard and making more money. Ideally, of course, we would prefer the money whilst playing at something else (boating, fishing or whatever).

Why do supermarket engineers presume they are at the pinnacle of their chosen field.

Is it because they started from domestic fridge repairs and worked their way up? (Note He didn't ask about refrigeration engineers.