I don't believe it's a zero sum game since, historically, money has never been a zero sum game. There have always been different currencies with varying levels of dominance. Even now, the USDs dominance has waned significantly since the world wars.
xmrbazaar.com gets more listings every day it seems like and I find myself using it more and more. I would never want you to be forced to use it, as that's counter to my ideals of self-sovereignty, but I do expect this market to grow over time and do my part to help it.
I don't want you to buy or use Monero if you don't believe in it, I'm not trying to convince you of that, Ive been just playing defense by dispelling false claims and by answering your questions as honestly as oissibke.