Not pointless at all. You need 3 keepers, the choice is an older one or a younger one. practically every team has an older third choice keeper, theyve got the experience, the presence and are more likely to be content with the role.
They might not play any games but they train every single day with the rest of them, and so have to be up to standard on a daily basis. They'll often even be the ones staying behind after training so that a few of them can practice freekicks or whatever on them.
He's constantly cited as a key figure behind the scenes for morale so hes clearly a good addition to the dressing room. Yes the role seems cushty from the outside looking in but he's earned the role. I also doubt he's on as much as 30k a week.