What's driving the Iranians to prance around like peacocks? Are they showing off to the USA or their neighbors? In recent years they've developed a very bad case of vanity. Vanity leads to envy which develops into hate which develops into war. It's the normal cycle of human evolution in progress. God must have created humans for the laughs.
The US Navy does flotillas too. In the Iranians’ case, a flotilla is pretty much the only time something like one of these minisubs would be available for viewing; the rest of the time they would be hidden away, just as the US’s subs are. So seeing their sub in “flotilla” paint is only to be expected.