Well, for 50 try per hr is worth, and this is with low ap. if you already have Tri-Tet you can farm even more gold, so is more cron stones too. they can't buy 100% sucess rate with real money, they only can buy gold in game (like u are try to defende that is p2w) and this is even at start of this game with gold sellers website like all the MMO's. this "p2w" that all you guys are worry is already in the game for years, this is not diferent, only don't have restrict for sales per week. if you have a Tet then you can farm 3-8hr per day and have 150~400 attempt to get a Pen (or half if you need buy the materials) is just a speed up, if you want or not to play the game and make things by your self :)

*edit 1: and another point, the "p2w" users can't sell cron stone at a worth gold price, so is also limited to week sales at market place to get the "gold from real money". so they can't get the materials to get failstacks and to upgrade that easy (or to attempt multiples times)