Well, I am one of those anti-pvp people and I can tell you why that is.
There are no winners in a war, or better the only winners in a war are the ones supplying the weapons, IFFFF those are located outside the actual war, because they supply BOTH sides of a battle.
The same holds true here, so to say I'm the weapons supplier as in I'm selling the cards you need to upgrade your deck.
When you say "the deck you need to win", you're ignoring that this cannot be true, because if two players meet that both have "the deck you need to win", there's still a loser.
Therefore your battles will become increasingly ever more expensive as you need ever more cards to upgrade your deck to ever higher levels, but in the end, no matter how high 1000s of players might upgrade, the amount of monthly prizes is limited, while the income of the weapons suppliers increases due to an ever increasing demand for ever more weapons.
You personally have bought from me cards for several 10s of 1000s of sat already, meaning I win EVERY month and I usually make more money per month in selling cards than an average prize in the monthly competition would be.
You'd have to be #1 in the monthly competition every month to beat what I'm making by staying out of it and I assume with increasing prizes for cards I'll soon make more money with selling cards than the monthly winner does.
Before you wonder, I'm by far not the only one who figured this out.
There are the traders who try to buy cards and resell them for a higher price, those are the ones jamboom wants out of it, but there are also several users like me who don't bother maximizing price, who simply frequently sell all the cards they get from the game, for a price low enough so even the traders buy them.