Here's an almost guaranteed way to make a successful software business. I've seen this happen over and over with tools in the industry.
Many software companies, especially startups, go through a certain lifecycle. First, they serve smaller customers because acquisition is easier. As they force growth to meet investor expectations, there's one well trodden path they can take, which is selling to enterprise clients.
Enterprise clients are better in every way to meet growth targets. They don't play around, and they pay a lot of money. But they also ask for a lot, and the software products become bloated with features. The products also simply become old.
Ignoring products with network effects, this shift to enterprise that most software tool companies go through opens doors every day for new companies to enter the market.
Think about all the popular software tools that startups use these days. They're more than likely to be from other startups. Linear, Brex, Notion, and others.
Looking for ideas? Just choose an area where the existing tools have become old and focused on enterprise.