Anyone who thinks that WA always has been an always will be a net contributor to the Commonwealth is a poor student of history.
They have also pushed for Secession on numerous occasions since federation, one time actually having a referendum which overwhelmingly favored such. Recently public opinion has waned on the topic, but who knows, at all other times Perth was no more than a country town. Now it's a self sufficient city with a wheatbelt and thriving economy and very good ties to a certain large Asian country that would ensure no one played with the goods.
And raising and running a defence force is kinda spendy.
The Australian federal goons are the only mugs playing that game. New Zealand just keeps a token force to stop piracy in their waters and that's about it. WA could just sign up to trade vs protection deals with China and wouldn't need more than a few patrol boats, they don't have the US hang ups the rest of Australia panders to. Again McGowan has shown he leans towards Asia as partners.
I bet a few QLDnrs would like to visit FiJi also!
I'd like to visit Fiji, but even if it was open it's riddled with covid right now, you are almost 100% guaranteed to get it if you go there. You actually would be safer holidaying in Western Sydney with no mask.