@TheGoldenMole
If you have a lot of free time to read about and talk to a person who you want to be like.. without having to worry about money.. then yes, its easy just like the actors do. And mind you, creating a personality is not that easy for even an actor. They try to adjust to that role by living in the conditions that the character is supposed to live. They adopt their mentality, even though for a short while, and their speech patterns and try to think like the character. You see.. Mind is a very powerful thing. It goes the way you want it to go unless it goes berserk and goes in its own way. So actors have to control their minds to get deeply into a role. However, some people are just like that in real life aka Robert Downey Jr. starring as Tony Stark and some people just give into the demand and lose their mind aka (arguably) Lt. Heath Ledger starring as The Joker.
P.S.- Acting is an under-rated art. You can’t just get into an intense role just like that. You have to prepare yourself mentally, physically and verbally(to say dialogues). Changing your personality in real life is much simpler as you do not have a set pattern of attributes to follow.