Here's a constructive critique: your post mentions the word "build" four times, but it does not mention the word "customer" once.
One possible exercise: Research 20 different potential customer niches, who might have jobs that need doing or frustrating issues they need help with. Reach out and interview a people working in each niche who could be potential customers, learn about their perspective, their challenges and frustrations, the existing tools or services they have tried, and how they fall short.
Another possible exercise: go read a "marketing for developers" book. I enjoyed reading Rob Walling's book "start small, stay small" a decade ago. Rob discusses some approaches to bootstrapping a business, including building things that people are already searching for. Some of the tricks and tools will be a decade out of date, but the mindset will not. It might be worth doing this to start thinking about what kinds of customers or niches would be more or less viable, and what mechanisms you have to learn about their needs or communicate your product/service ideas to them, to define some filtering criteria, before starting to research potential customer niches and interviewing people.
A third possible exercise: ban yourself from using the vague word "idea" when writing and thinking about possible businesses to build. Instead, read the first few chapters of a marketing textbook, and only allow yourself to use terms and language defined in the marketing textbook when writing and thinking about what you are going to do next.
https://startsmall.com/
https://open.umn.edu/opentextbooks/textbooks/principles-of-m...
(take all these suggestions with a mug of salt, i'm merely a professional builder of software things, i don't have any experience with marketing or how to bootstrap a business)