nah, 1b isnt that much if ur only using the interest its only about 150-200M a year, i would prob start buying all the rare items so u techianlly b a monopoly owner of items...ex. start mass buying freezing potion/rarity 98+ stamps, and eventually i think ppl will need to ask u for them and u can name any price
When you hit 1b+, you won't really care about inflating r98/r99. Trust me~ 
EDIT:
Same things goes for people that collect r99 gallery, 1500~1600+ r99s just to I/J quest. Istaff and WODF is fun and all, but after few months, it gets boring because it becomes a routine for you to throw them in SDB waiting for buyer. 
But you will be surprised even at 1500~1600, you still fail quite a number of quest while going for level 50.
Edited by neopetsexploded, 09 October 2014 - 06:59 AM.