Why are so many people building Stealth, when will the construction get finished :p

I came across many founders on LinkedIn who have added building Stealth startups in their bio/ description.

Here everyone talks about job and salary. Though there isn't any meaningful useworthy discussions other than office gossip, salary etc. the engagement is good. Any apps which are exclusive for startup founders and enthusiasts?

Every other person on LinkedIn is building something or in stealth mode ! Exciting times ahead I guess ( I’m looking for opportunities in business development and sales to improve my selling experience. Any founders out there ? I want to...

So it's basically about when something good happens to you, like getting a new job. Do you believe in telling your friends or relatives in advance, before joining? Or do you prefer to share the news on the joining day through LinkedIn or...