A while ago, I was in the same boat. Why try to recreate GitHub, or Uber, or Salesforce, or Facebook? And once I discovered any competitors in my idea's field, I would chalk it down to "not worth trying" and call it a day. But then I realized, if my town can have 3-4 Chinese restaurants with the same exact menus (probably supplied by the same exact distributors), and they've all operated continuously for over a decad…
We're faster, simpler, privacy friendly, cheaper, etc.
Most leading SaaS businesses have proven there's a market, but they're vulnerable on one of those key differentiators.
Sure, you might not conquer the market, but it's probably a safer way to build a lifestyle business than trying to come up with and market a novel idea.
Much easier to find forums of people complaining about product X not doing Y and fill that gap.