First off an expansion costs $40 which is more than a mount cost not half of it. Second, you don't need anything off the MS to succeed in this game. Not even retainers. And no, they aren't an advantage for hoarding gil and having more MB listings. Because 99% of the high tier gil items that drop from places like eureka are, again, cosmetics you don't need. Crafted gear? If your hemorrhaging gil, you likely have the crafters required to MAKE the stuff yourself anyway.

None of it is required. People are just under that illusion because they want it. Need and want are two different ball parks.