It's not a dumb question. I always want to ask myself this question before developing anything. A lot of times I find the site is great that is developed, but it does not make money. Hindsight is 20/20. After developing a handful (and learning the hard way), you learn to think a little more clearly and think "can I make $10,000 a year doing this?" You need to remove your emotion and really ask yourself - without being a marketing genius - can this site succeed at making me some residual income? How much qualified traffic does a domain have? Seriously, if you get 10 unique visitors a day, how many do you think you can honestly convert to be paying customers / clients and/or ad clickers?
Moreover, start small. Put up a very simple page and tell people what you can do. Ask them to fill out a contact us form, or call a dedicated phone number. If you get enough hits/leads you have an idea it is worth developing. Before spending $5,000, know what you are getting into. The formula should be something like
Risk = how much time and money you put in within the first 6 months (by the dollar)
Return = how much money you can make per year on this
So, if you calculate Return divided by Risk and your result is 10 or higher, you might be onto something. If you are going to put $10,000 in developing it to make $5,000 a year... It is a very risky investment, unless you have a lot of spare cash to tie up for a few years.
Of course, if you can drive traffic there and be profitable, even better. Just some more thoughts on the topic.