Just wait until that startup starts feeling like a real job. Then come back and comment on how different it is. Personally I have found working for myself to be quite different then doing the same thing for someone else. I have to find the work, I collect 100% of the revenue and as a result the preverbal buck stops at my desk. I sleep well.
I don't know, maybe the problem is that my perception on freelancing is based on a non representative sample: For example I've browsed rentacoder.com for a while: my impression was that the market is extremely saturated, most of the tasks are quite boring, time consuming, low-payed and not much fun. Did not seem to be better than a day job. Being a well-recognized, top freelancer with special skills and good connections: that's good. But being an average freelancer does not seem to be very appealing.
On the other hand at my startup I can create things which my bosses and customers did not even think of. Most fun software problems are not eceonomical to solve in very high quality for one client, but it is economical to solve if you can sell it as a product to lots of clients. This possibility of 'scale' makes startups very different. On the other hand the success rate it much lower. I have failed projects behind me, I know what failure is, but I've learned a lot from them, and still I try again (beside my day-job).
Rentacoder and elance are the absolute worst places a decent freelancer should look for work. Even craigslist is head and shoulders above them. I've found lots of $75 - 100 / hr gigs on Craigslist, but they'd laugh me out of Rentacoder for those rates.
