I don't thing that is necessarily the case. If your model is to sell the software as a SaaS, then yes it gives you a disadvantage, because someone else can just take it and sell the same thing without paying for development. Same thing if you sell a packaged product. If you sell support, you have a slight advantage, because you have more expertise in your product since you created it, and can make changes directly to it. But then it can be hard to find customers willing to pay, and you have an incentive to make the product difficult to use so more users require support.

I think the ideal situation would be where you are paid for the development itself, rather than selling the resuling software. Maybe with a pool that interested parties can invest in for initial development, new features or continued maintenance, like kickstarter or bug bounties. But that probably wouldn't have the high margins that the software industry has become accustomed to.