Pokemon GO, unlike Niantic's first game Ingress, has a whole lot more levels. In fact, there are currently 40 levels in Pokemon GO, and it's likely that Niantic and Nintendo will add even more in the future, to keep gamers interested. As expected, when you level up, you'll need more and more XP or experience points, to reach the next level. But it looks like some gamers are not to happy with how the game scales with higher level players.
Reddit user, Riggnaros, posted on the Pokemon GO subreddit about the scaling issues. Riggnaros is a Level 30 in Pokemon GO, one of the very few to hit that level - after all the game has only been available for about 2 weeks now. He says that the "scaling is WAY off in every area and needs to be adjusted". Continuing to explain that Pokemon captured at level 30 give the same experience points as those captured at level 1. "It makes no sense that a 10cp Pidgey should be giving the same xp as an 1600cp Scyther." Definitely something that makes sense, especially seeing as the more powerful or stronger Pokemon are a bit tougher to catch, and users should be rewarded for that. Riggnaros also says that it would be tough for anyone to play the game without spending any money on the game. Keep in mind that Pokemon GO is a free-to-play game from Niantic and Nintendo, so there are in-app purchases here.
A Twitter user put together a pretty handy chart and spreadsheet, showing how long it would take for someone to level up, and according to these projections, it could take players nearly a year to go from level 38 to 39 without buying anything in the game. Remember that you can only get 100,000 experience points per day, so you are a bit limited. That's quite a long time to just go up one level. And that would mean getting 100,000 XP every day for 365 days, which is likely not going to happen for anyone.
With Pokemon GO still being a pretty new game, it's not surprising to see that there are a few kinks that need to be worked out. Niantic and Nintendo will probably work them out over the next few updates to the game.