When we started CircleCI, there were at least 3 other things that were pretty much the same. In addition, two similar services had died, and one had pivoted to be a PaaS. There was also Jenkins, TeamCity, Bamboo, and lots of other alternatives. And then over the next two years, there was at least 20 competitors that started, some with significant funding.

I agonized over so many competitors, and none of them mattered. If you're going to do it, just do it.