You can be both large and irrelevant. Facebook is perhaps the best example of this. Reddit feels headed in the same direction.

Facebook is incredibly relevant. It probably has more impact on more people's lives than Twitter or Reddit. Facebook isn't cool anymore. But for the 30+ crowd, especially the non-college educated crowd its huge. Tons of small businesses use it to host their "websites", the community groups are huge, parents / family groups, facebook marketplace totally replaced craigslist for a lot of people.

Define irrelevant, because if it has eyeballs...

If early adopters have moved elsewhere, and it's all late-majority, it will have the most eyeballs right before it dies out.

Facebook has the eyeballs. I don't think it's relevant anymore

What's the criteria for relevancy, if not "do people still use it"?

Are you innovating? Are you top of mind for people? Is your tech transforming people's lives?

I use electricity every day. Is electricity relevant in most contexts for me? Nope. I drive a car every day. Is the type of car I drive relevant in any way? Nope.

Your life as you know it would disappear if electricity stopped flowing tomorrow.

Facebook is no longer the trendsetter but it still influences the daily lives of millions of people and will probably, once again, have a major impact on who the United States next president is. Facebook is highly relevant.

Would your life as you know it disappear if Facebook disappeared tomorrow?

Facebook is a cancer to our society. Luckily it looks like most people moved on an now it's a ghost town.

You're confusing sufficient with necessary. "Your life as you know it will disappear" is an absurd necessary bar to determine if something is relevant or not.

> Luckily it looks like most people moved on an now it's a ghost town.

Ah, you're just unaware of Facebook's DAU/MAU trends. They're not hard to find.