For me, the worst kinds of unlockables are ones that are randomized or only appear at certain times. I absolutely hate when I see a cosmetic that I like, then when I look up how to get it it, it's like, "Oh, remember that super busy week where you had no spare time? Well, it was available for a limited time then to those who grinded or bought enough currency. So you missed out, but don't worry, keep logging in every day and maybe in six months you'll get another chance to get it."
And obviously any sort of lootbox or pseudo-gambling mechanics are predatory trash as well meant to suck as much time and money out of you as possible. The ability to buy in-game things has butchered game design beyond recognition. I believe that if you want to satisfy your own thirst for excitement, you should use special services for this. For example, on
https://kaszinoworld.com/hatoslotto/ you can find great bonuses and other benefits from the game. However, you shouldn't transfer this part of the excitement to video games.
