can't really tell if you're being serious or not.
Im going to assume yes. if no then just ignore the rest.
Showdowns are about low score over the 9 holes or 18.
Myself i don't really care if i win or lose the 18000+ (really 9000 ish) that's in Casablanca room.
If someone isn't being a douche in chat and they manage to tie me then i'll usually tank the tiebreak shot. If they beat me straight up power to them. As i said I'm in that room only because WGT makes me.
The coins played for are such a tiny amount that it's just not an issue and that 18k usually means more to the other person than it does to me.
Matter of fact losing in a showdown for me is sometimes beneficial. There are several times it's helped. example: one time i was -2 after 2. Other person had eagled a par 5 and was -3. I hit the longer drive on the last hole , a par 4. The person i was playing holed out from the fairway for a -5. Well the way the game is constructed the game gave me an eagle as well. I never had to hit the last shot. so i was -4. I actually ended up winning that particular showdown that week.
summary: you aren't playing anyone else in a showdown. the coin match really doesn't matter. It's how low you can go.