Okay, I'll give it a shot (for the second time) since there is a short list of people who qualify. I'll even give you a few takeaways for your money's worth.

Most people do not care about your streak or habits.
I usually only bring up my writing streak to note certain milestones, otherwise I don't bring it up unless asked. When I tell people that I've been writing for over a year or now two years, they generally don't have much of a reaction. "Oh yah? Cool." "Nice!" No, "Really? How did you do that?" or "WHY did you do that?" People have their own issues they're dealing with, and I don't think they care about what someone else has going on unless it's something that can benefit them. Maybe people don't understand the feat, itself. I don't understand how someone can run a marathon, but I know there are people who can run one as easily as I walk to the mailbox.

It takes a long time to make a habit "stick."
Forget 21 days or 66 days to a new habit. It takes a lot longer than that to make a habit "stick." What I mean by "stick" is a habit that is automatic. You don't set reminders. You don't think about doing it. It just automatically happens. There were times even after a year of writing when as my head hit the pillow, I had a moment of panic trying to recall what my post was for that day. Of course, I had to log in and check the site countless times when that happened. I can't pinpoint when it happened, but now that I have crossed the two-year threshold, I can safely say the habit of writing has stuck.

Writing in public makes a difference.
I remember when I first started publishing articles on Medium. I was always anxious and my heart started to beat faster when I was about to hit that publish button. Who will read it? What will people think? Will I get criticized? All worry for nothing. Hardly anyone is reading anyway. After you hit that publish button everyday for awhile, the anxiety goes away. Writing in public also has a level of accountability not afforded by writing in private. I'm not against writing privately; I have a gratitude journal that I write in every evening. If you want to write for an audience, however, the sooner you get over the fear of hitting that publish button the better.

I have noticeable improvement in my speed and quality of writing.
You don't have to be writing a novel or formal essays to improve your writing. Writing every day about whichever topics you like is enough to exercise the writing muscle. After two years of daily writing, I notice the differences now compared to two years ago. I can craft emails much more easily. I can produce business documentation faster, and the writing is more clear and easy to understand. The biggest improvement has been my ability to identify the target audience for my writing. Today, I focus much more on the needs of the audience instead of my own needs. I feel like writing is my superpower that few other people have.

Writing is a gift that gives three times.
The first gift of writing is the gift you give yourself as you are writing. The act of writing can be cathartic, and I find the process quite enjoyable. The second gift of writing is the gift you give others when you publish. If at least one person read your work and had an emotional reaction or changed a viewpoint or decided to make a change, it was worth it. The third gift of writing is the gift of history. I am jealous when I read about people who have been keeping a diary since they were teens. I wish I had started writing every day decades ago. I now have two years of posts that I can reference to observe how my interests and viewpoints have changed over time. 

Who's ready to start a writing streak?