First of all, you should think of this as an investment, not an expense - like that time that you went to the gym, you didn't think of it as losing money, you thought of it as investing in your looks.
Second of all you don't really have to hire a full-time UX expert. If you have a small business, you could go with a consulting firm to set things on the right track for you.
But picture this: you have 10 programmers working on your product, they constantly add new features that really kick ass in the industry but nobody is using them. Maybe because they are hard to use, maybe the controls aren't in the right places, maybe the copy isn't great and you don't really know how to ask your potential customers what's wrong. It may be hard to realize it but you need a fix.
The idea is you could have 9 programmers and a UX person doing a better job. Your product kicks ass only if your users say so!