I am an honest man by nature, I can't talk, I can't kiss up, and I suffer a lot in the real society. Who can teach me how to change?

This aspect of personality is innate, and it also has a certain relationship with parents' education.

But people will change. When driven by interests, you will put aside your conscience and kindness, and you will do anything for the future.

otherwise, you will always be at the bottom of society, and you will be unwilling.

You need a blow. At the bottom of society, there will be countless people to give you a blow. Then you naturally learn to be tactful. Take your time.