I am a straightforward person, and I don't like to pretend. What is my personality in these two things? Is there something wrong with my brain? What should I do?

After reading what you said, I have some personal opinions for your reference:

I think your position is right about drinking with the leader. After all, some people can't touch alcohol. It's just that it would be better if you expressed it in a more euphemistic tone, or told the leader your real situation in private. If you put yourself in his shoes, you will definitely be unhappy. However, as long as he is not that arrogant and haggle over every ounce, he will generally not take this matter to heart.

As for the second thing, I believe your original intention is for his good, because his behavior is not worth it. However, everyone has their own views on things. Maybe he just likes the products of that brand, so we should respect his preferences and opinions.

From two things, we can see that your personality is very self-centered, your communication style is a bit direct, and you rarely take into account other people's feelings in communication. Accordingly, my personal advice to you is: when dealing with people, always put yourself in others' shoes and think from others' standpoint. Maybe your views and ways of doing things will be different! !

Finally, I have a personal opinion on your point of view: indeed, life is too short, we should not live for others, and everyone wants to live their true selves. However, this society is not our own, and the world will not revolve around us. Therefore, we can't avoid communicating with others, and we also need others' help. Sometimes we think about others a little, just to make our way less difficult.