Like most things in life, it usually boils down to money or time.

If you have the time, you can get the very best items in the game. Arcane and Mythic items drop from Elite Gold chests that can be obtained from the Elite bosses. Sure, you probably need a good group, but it is entirely doable to farm Elite bosses.

If you don't have the time, you can shortcut by spending money. That doesn't invalidate the fact that you can obtain the very best items without spending any real money.

At the end of the day, those people who do spend money on the game make it so that everyone can play for free. We sincerely appreciate the users that do support us. Rather than being jealous of those who do have Platinum, you should likely thank them for allowing us to operate the game where you can play for free.