[Incel]

There are incels who doesn't share about their inceldom (except in some incels groups, chats, forums, social networks online, but not every time). Some of them are keeping it a secret. There are those ones who even pretend to had/have a girlfriend or pretend to be volcels.

Why? Because some of them are afraid that they'll be associated wrongly with the worst of the rest (for example with those mass killers or with the rotting pessimists who are proud to be "blackpilled") and being wrongly accused of being crazy and/or stupid and lazy.
Because some of them feel shy to say they're incels and being ridiculed by those tactless and/or rude friends, colleagues, relatives and others.
 
In a sentence: there are more incels around you than you think/imagine.

[Alexa]

It is quite understandable.

[Good incel]

They have good reasons to do so.

[Ineedloveandpassion]

There are those who don't know "incel" as a word, so... where is the point to do so?

[SEO]

Well, we're talking about secretcels.   Not sure if it's a correct term.