The expectation that you could get an apartment that size in central NYC without being a billionaire is also a lie
I think they explained it, the reason they could afford it was because Monica’s grandmother lived there, and they’ve been paying 1980s rent because of rent control or something. Something similar for phoebe as well. Anyway show never explains how joey/chandler/Ross can afford those big houses.
Hi, Chandler and joey’flat is not that big, it was actually the joke between characters often and Chandler had a good job anyway. Ross was good with money and his parents favourite so I think he got more money from them.