I believe the most beautiful and elegant answer to this question is from Churchill. "On a peaceful afternoon, I sit at my desk on which there are only a pen and scores of white papers; I write. And this is the most beautiful thing in this world [1]." And, to be pragmatic, there are many advantages by writing a blog.
To write is to think better [3, 6].
Exhibit oneself
Practice writing skills [2]
Other reasons in these three articles from Weipeng Liu [3]
Write down one's beliefs and values [4]. Build the value hierarchy.
After one has read many books, he wants to write. The inspiration is from [5], a blog of an art professor.
It is easier to share with friends about articles, books, movies, and thoughts, like what she does [5].
In our blood, we want to receive the acceptance, agreement from others. And we want to be corrected by others [13]. Just like the academia, when a researcher finds a great principle, he wants to share with his peers, or to be more general, with other human-beings.
To publish a book one day, just like what they and others did [7, 8, 11].
I want to write a fiction one day. I want to use the good expressions used in these books [10].
Technical blog. To help others avoid pits (potential detours) [9].
To keep interest dairies, e.g. about clarinet, tennis, hiking, etc. [12].
Sometimes I really don't want to write and just want to waste my time doing easy things.
But after I read some books (especially [6]), I come back again to want to write. And after I did it, I appreciated that I did it.
Postscript (P.S.): The principle of the content of the writing: Only write the content that is useful to you and your potential readers [3].
P.S. No. 2: Recommended blog and personal web:
1 Xiaolai Li
2 Weipeng Liu
3 Junbo Zhao's micro blog
4 An art professor. https://www.douban.com/people/malingcat/
5 Brother vczh. http://www.cppblog.com/vczh/. [9]
6 Junbo Zhao. An EE professor.
7 Yi Wang, Tsinghua University
8 Fei-fei Li
9 Daniel M. Kammen. A professor with UC Berkeley.
10 Ke Wang, a computer science professor.
11 Philip Guo
12 Xuesen Qian: The Letters
13 The Albert Einstein Collection Volume One: Essays in Humanism, The Theory of Relativity, and The World As I See It
14 -
15 [7] Give you a bullet. A Cambridge professor.
7/23/19
Reference
[1] The Joys of Writing. Churchill
[2] A high school exam paradigmatic article
[3] Weipeng Liu. Dark Time.
[4] Junbo Zhao's micro blog.
[5] An art professor. https://www.douban.com/people/malingcat/
[6] Treat the time as a friend.
[7] Give you a bullet. A Cambridge professor.
[8] Bill Clinton's saying
[9] Brother vczh. http://www.cppblog.com/vczh/; and www.hysteriz.com
[10] Weidong Hou's notes in Chinese officialdom (a fiction) and Kane and Abel (a fiction)
[11] Philip Guo. Ph.D. Grind.
[12] Kenichi Ohmae. Off school — will play will be successful.
[13] A zhihu answer for the question: why do you write an answer in zhihu.com?
为什么我要写博客
2019年7月23日
我相信这个问题的最美丽和优雅的答案来自丘吉尔。 “在一个宁静的下午，我坐在我的办公桌上，那里只有一支笔和几十张白皮书;我写道。这是世界上最美丽的东西[1]。”而且，要务实，写博客有很多好处。
写作是为了更好地思考[3,6]。
展示自己
练习写作技巧[2]
来自Weipeng Liu的这三篇文章中的其他原因[3]
写下一个人的信仰和价值观[4]。构建价值层次结构。
读过很多书后，他想写。灵感来自[5]，一位艺术教授的博客。
与朋友分享文章，书籍，电影和思想更容易，就像她所做的那样[5]。
在我们的血液中，我们希望得到其他人的接受和同意。我们希望被其他人纠正[13]。就像学术界一样，当研究人员找到一个伟大的原则时，他想与同龄人分享，或者与其他人类更为一般。
有一天要出版一本书，就像他们和其他人一样[7,8,11]。
我想有一天写小说。我想使用这些书中使用的好表达[10]。
技术博客。帮助他人避免陷阱（潜在的弯路）[9]。
为了保持利益，例如，关于单簧管，网球，徒步旅行等[12]。
有时我真的不想写，只想浪费我的时间做简单的事情。
但在我读了一些书之后（特别是[6]），我又回来想写。在我做完之后，我很感激我做到了。
后记（P.S.）：写作内容的原则：只写出对你和潜在读者有用的内容[3]。
附：第2名：推荐的博客和个人网站：
1李小莉
2 Weipeng Liu
3 Junbo Zhao的微博客
4一位艺术教授。 https://www.douban.com/people/malingcat/
5兄弟vczh。 http://www.cppblog.com/vczh/。 [9]
6 Junbo Zhao。 EE教授。
7王清，清华大学
8费飞飞
9 Daniel M. Kammen。加州大学伯克利分校的教授。
10柯望，计算机科学教授。
11 Philip Guo
12薛学森：信件
13阿尔伯特爱因斯坦收藏第一卷：人文主义，相对论和我看到的世界的散文
14 -
15 [7]给你一颗子弹。剑桥大学教授。
参考
[1]写作的乐趣。丘吉尔
[2]高中考试范式文章
[3]刘伟鹏。黑暗时间。
[4]赵俊波的微博客。
[5]艺术教授。 https://www.douban.com/people/malingcat/
[6]把时间视为朋友。
[7]给你一颗子弹。剑桥大学教授。
[8]比尔克林顿的说法
[9]兄弟vczh。 http://www.cppblog.com/vczh/;和www.hysteriz.com
[10]侯卫东在中国官方（小说）和凯恩与亚伯（小说）中的笔记
[11] Philip Guo。博士研磨。
[12] Kenichi Ohmae。离校 - 将会取得成功。
[13]一个智慧回答这个问题：你为什么在zhihu.com上写一个答案？