For example, if you work in finance and notice that the company you work for can't find a teleconferencing service that does what they need, it would be fine to start a startup to build that.
At the same time, experience can often mislead you into thinking that your problems are everybody's problems. Experience gives you a head start, but you should still do customer research to confirm the "traction potential" of your proposed business model.
However, I strongly believe the most important thing for an early-stage start up is passion around the space/solving the pain points. The main reason is that working in a start-up is really hard and, at times, soul-draining. If you hit that depression phase and you aren't 100% committed to solving the problem you'll never pull out of the death spiral.
That being said, if you're passionate, you don't have to be an expert as long as you commit to becoming an expert quickly. Tons of breakthroughs happen when intelligent novices enter a space without the preconceptions of the existing leaders.
But then again if you know little bit about the field and can do your market research before continuing further to gain experience or to employ someone go ahead and do the market research for your business idea then you know if your idea is worthy of going forward.
Now that summer has started, we've begun work on a different startup (a new type of search engine, sort of...), but it's kind of new territory. We're pretty confident we're aiming at a fairly large target audience, but still scared as this is completely outside our area of expertise.
do you have a 100% passion for CRM?