I really doubt "literally" every software you used or worked for has multiple competitors doing the "exact" same thing. VC money can temporarily prop up multiple competitors doing the same thing, but over time, winners definitely spring up.

A lot of software that on the surface does the "exact same thing" often has different nuances, either to the business or the product that makes them appeal to different niches in the market.

Understanding the nuances and exploiting the market niche is your only goal when starting a business. It's not something you ever do or think about when working on software, but people who strike it out on their own quickly realize that simply building is not enough, you MUST give people a good reason to use your software. Just because you don't see or understand the nuances, does not mean they are not there.