what is the hardest realistic rating to get past?

I got past 1600 then had a crazy loss streak

The hardest sensible ranking to surpass for most gamers is frequently regarded as the International Master (IM) title. Beyond that, attaining the Grandmaster (GM) title is even more difficult and requires remarkable skill, dedication, and overall performance in tournaments. The majority of chess gamers in no way obtain these titles, making them the hardest to achieve in the chess world.
what I meant by realistic is that a lot of people will get to, get stuck at, or surpass. Most people do not get IM

I got past 1600 then had a crazy loss streak
When I first got 1600 rated in Blitz I also lost many games but luckily I'm back at 1600. Also when I was 1300 I had a difficult time getting to 1400. So I would say that for me it was from 1300-1400 and 1500-1600.

Took me 1 1/2 years to get past 1200, I guess that's usually the rating where beginners start to be come a little intermidiate
I would say the 1000-1200 was the hardest to get past for me