Can downvote me all you want, it's likely you and everyone agreeing are mediocre at business. I'm not even trying to be rude or contrarian. Everyone who hides there niche is almost always a very small business owner. I've come across a few 8 figure sellers in ecommerce who hide their niche and they almost always suck as people to talk to when networking.
If you're good at what you do, you don't hide it. Imagine Steve Jobs hiding the Mac and telling people it's a niche secret. No if you're confident in your business and product you scream it from the rooftops even if you don't need the distribution. If you're a shitty low end dropshipper, SAS company, or even worse a brain dead person with a physical location thinking someone's going to steal your carpet business in Austin, Texas... then you hide your niche. I just think this mindset is cancerous to business and humanity so I vehemently reject it.
I sell lint rollers on Amazon.com my brand is PetLovers.com. if you want to compete feel free our competitors are 3M, and Chinese sellers totaling 50M/year in sales. Even if our competitors weren't big I wouldn't be afraid. Feel free to hop in we're at 7.5M in revenue this year. Doesn't mean you'll match it though.
Both still stand as small businesses, are their antique sellers that make millions pretax annual profit? Maybe. But I'm guessing 95% don't. And people going to thrift stores don't even clear 6 figures usually, but yeah I'm aware some do. Ecommerce is my industry so I'm not speaking out of ignorance completely. I don't know much about antiques but I've visited many antique stores and I would imagine most are high five figures or low 6.
So ill revise then, guarding niches are for very small entrepreneurs who can be infringed by other small entrepreneurs who would pursue microniches. But they're still inexperienced or low skill ceiling entrepreneurs. That's not inherently bad, not everyone should pursue being a millionaire or billionaire. But if they're not and don't have high levels of success in business which is unfortunately factually quantified by revenue or investment money raised, they shouldn't speak with authority... because they don't have any.