Yeah, I'm fairly new too. I just barely hit level 90 last week. There are some people I find who are like level 162. I find that I don't have enough coins to upgrade all of those 5* characters that they put out for the limited events, so I don't end up getting very many of them. I focus on my best characters instead. I have all of the 6* Bloomables right now except Nerine. I would never sell a 5 or 6*. Do people actually do that? Is there a benefit besides the bond crystals?