Why do Vegans have to let everyone know they are vegans?

Attention seeking behavior, no point being a vegan if you can't annoy people with it.

Depends on what you mean. There's those that only bring it up when necessary like when invited for a meal or are ordering something from a restaurant, etc, etc. And there are those who bring it up for attention.

Q: How can you tell if someone is a vegan?
A: Wait 30 seconds, they'll tell ya!

It gives them a sense of moral superiority.

People normally eat 3 times a day so the subject of food does get brought up often. Also, veganism is a bit of a lifestyle and people often talk about the ways they live. And obviously vegans feel strongly about it, they want to share what they are passionate about.

I'm a vegetarian. It's a normal part of my life. It's a thing I do because I want to. People question my choice a lot, and often get argumentative about it. I don't feel like explaining myself to everyone I meet, and I don't really like arguing over my meals, so I mostly just try to avoid the topic, particularly around people I don't know very well.

It is unfortunately, quite difficult to keep it secret. I started a new job about 6 months ago. It took about 2 weeks for everyone to figure out I was a vegetarian because they kept ordering subway and people kept asking me why I didn't want to eat lunch meat subs with everyone else. I'm not about to lie. I just told them the truth.

People who eat meat often question why we feel the need to tell them we're a vegetarian, but I'd like to know why other people always ask me why I don't want to eat what they're eating. If you don't want to know, don't ask!

So true, and wish to diss anyone who isn't. It's like a bad religion or something.

I only tell someone I'm vegetarian if I have to. For example, at work the company buys us pizza every wed. If I didn't tell them i'm vegetarian then there would be nothing for me to eat! I never just tell someone I'm vegetarian because I want them to know. Honestly to me it seems like the people that do are doing it for attention and recognition. I have friends and coworkers I've known for years and they still have no idea I'm vegetarian.

so you don't feed them animal products

or

they can decline to eat animal products

well, they hope you will save the lives of animals by not eating them!

they just want you to be interested and they want to talk about it thats all they talk about. they just dont care about anyhting besides getting everyone to turn vegan thats why many of them are also activists.

It's common for people to talk about the things they are passionate about.

Its no secret. Why would i want to keep it a secret. Its not embarrassing or anything.
Oh, does it make you uncomfortable?
Too bad.
You eat animals.
Karma.

There is no one more self-righteous than someone that has done something difficult.

They feel they are right or they would not have attempted it. Then, because they accomplished it, they assume that everyone should do it, and be able to do it.

It is just human nature.

You probably won't notice the ones who don't tell you. It took my coworkers 6 months to notice when I went vegan.

Same way meat eaters let everyone know they are meat eaters.

I can't remember if a person has ever told me or I asked. To each their own.

I've never met a vegan, and I've met a lot of people. I know they exist only because you see vegan options on some menus. For the pacifistic vegans, I'd say they let everybody know so that they can tell others about their restricted diet.

to make others aware of horrifying animal abuse going on within the closed doors of slaughterhouses

Cause we are examples to follow
We have to tell how happy we are to have renounced to the meat

they don't nearly as much as meat eaters do