There are 3 kinds of people. Let's call them versions 1, 2 and 3.
Version 1: won't change
These are the people who hold on to their pasts. Once they are labeled something, based on something that they did or something that they told; they tend to retain that feature forever. Change is not a word even in their electronic dictionaries.
The bug with this version is that people are never born great. Which means imperfections are engraved on marble for these kinds.
Version 2: will change when proved wrong
Upgrading to this version requires this version. It's a catch-22. In other words, if you can change yourself, then you can change yourself into a person who can change themself. Let's forget about the paradox for now. These people change when they are proved wrong. If they participate in a debate one of the following is essential: they win, or they switch sides.
Version 3: proactively seek change
This is the highest version one can reach. People of this kind change, and think of all the ways they can change, without the need for being proved wrong. They are like scientists - constantly redefining their theories, striving for perfection.
And an upgrade to this version is rarely complete. Most often than not people behave like v3 only in some aspects of life and remain in v2 or even v1 in others. But the very nature of v3 is such that it seeks out which areas have failed to upgrade to v3, and upgrades those areas too.
Thus, slowly, the person is readied to attain eternal greatness.
How to upgrade
The only glitch in the process is that upgrades aren't automatic. It always takes a self initiated command. And you are the administrator of your machine.