Agree, but slightly dis-agree, as we all have noticed that the "under educated" (about fish) go in to pet shops with there credit cards out, now the sales person, see's a quick sale, and there goes, a tank, a heater, a filter, some neons, a pleco, a cichlid etc. 
The person thinks that when they go home, they set the tank up straight away, and watch there ever lasting fish, without knowing the big fish they brought ate the little fish and so on.. 
So yes it does pay to learn before hand. 
 
The second thing, is they hire young student's  
(no offence to the people who share the passion and work there)    
{this is my experience}  :evil:  
who don't care, or care to learn about fish, only there booze money, and will sell you fish, having no clue what they are. 
 
So its not always the buyers fault, right?