I think you are missing the point. Yes, it would have been nice if these parents had been able to save enough money for their retirement. I'm sure, given the option, that they would have. Apparently, however, their income did not permit that and they chose to invest in their children instead. There is no indication that they decided "to enjoy their money now" or that they ever planned on having their children permanently support them. Rather, it seems that they are simply people of modest means who are doing the best they can under difficult circumstances and to insult them for that reason - as you and the letter writer both do - is cruel and unfeeling.