No LinkedIn, not you, you boring Ted Talk humblebrag.
I doubt many are being serious.
Business culture (at least in the US) is so steeped in lying and general fake-ness that in-group signaling as "real business person" involves public performances of bullshit.
It's what you're supposed to do in interviews: bullshit just the right way, to show you understand the game and are willing to debase yourself to play it. Otherwise you're "risky", either due to excessive commitment to ethical principles or to being too clueless or inept to play the game right. That's what's going on, on LinkedIn. "Humility" and "realness" even have to be faked just the right way.
It's incredibly gross.
If you crack and admit it’s fake, everything falls apart and it’s your fault. Expulsion out onto the street follows.
Even worse, now everyone else is going ‘how could you be so dumb to believe it’ and/or ‘you sure fucked up by admitting it was fake’ all at the same time.
Not necessarily mutually exclusive. It's like professional wrestling, stage magic, or politics. Some lies people really love.