What does it take to get over a 2k rating?

For example:
What skills must a player master?
What books must he read?
Who should he study?
etc.

I'm not only asking this for my own study and training, but I am also very interested in the performance and psychological aspect of the game. So I am very interested to hear thoughts between diverse minds.

So please do reply!

Broadly speaking, there are two skills that matter in chess - evaluation and calculation.

Evaluation is essentially the skill to recognize the most promising candidate moves or plans in a position and calculation is your ability to visualize the consequences after x moves ahead and choose the best move.

In order to improve calculation skills, you need to train your mind to be able to correctly visualize a position several moves ahead. Pretty much the only way to develop this skill is through practice.

To improve evaluation you need to study a variety of typical positions in the opening, middlegame, and endgame. I don't believe there are any books that could be considered "a magic bullet" to improvement. In fact, many books oversimplify a lot of stuff and could just stunt a player's development. Imo the most important factor is to be exposed to the thought processes of strong players as much as possible, either through books (collections of annotated games) or personal interaction (also, in the 21st century there are tons of youtube videos that are very good).

Join a chess club, play a bunch of games, talk to stronger players about the game, watch them analyze. There's no substitute for this type of learning.

Practice and study. Tactics are easy to do on your own as is reviewing your games, etc. Having stronger players comment on your games, even just casually, is very useful, as they will point out strategic ideas that will not occur to you and which a chess engine won't "explain". That's true even well past 2000...

But also: consistency.

People tend not to recognize this, which is why so many chess players consider themselves underrated. They evaluate themselves based on their peak performance while the rating reflects their average performance. Very specifically to this question, though, I find that consistency is the biggest difference between 1850 players and 2050 players.

Agreed. Just about every 1850 thinks they can play like a 2050, and most of them aren't so much wrong as missing the fact that a 2050 plays like that all the time.

Or can play like 2250 sometimes when a 1850 cant ?

Performance and exposure to tournaments where you can compete to achieve this rating.

The mental faculties of being "able" to play at a 2k+ rating are a different question than what it takes to "achieve" a 2k+ rating.