I will possibly bootstrap a software product in the near future, but the hard part for me is to decide in which market I can find a niche. I find it hard to develop a new solution in a crowded market. I want to develop a product I am convinced of, but doubt often gets in the way, especially if the market is crowded. I also wonder how these services get their first paying customers.
I am going through the same thing. Everyone says enter an existing market because you already know people are willing to pay for it. But I am afraid that the existing solutions have soaked up all the customers. How am I supposed to get those customers?
Make sure that the market you're going into is growing and not shrinking. In a growing market, there will always be new customers.
People like choice. You don't have to compete feature to feature with your competitors. Stand out somehow. Identify how you truly differentiate and make sure that everybody knows this.
The good thing about an existing market is that people are already looking for what you're selling. All you have to do is be there, be different and be findable. The bad thing is that the competitors are mature and it takes a lot more effort to actually compete.