[CyberFonic]

I think your concerns are very valid. However, I also believe that the target market for your product makes a lot of difference. The two extremes are:

Your target market is non-technical, then demonstrating your MVP to potential customers should help validate your idea. The feedback will ensure that you build the most important features first and thus start delivering value to your customers. NB: a customer is somebody who pays for your product. Non-technical prospects are more like to focus on their core competencies and not be inclined to copy something that they could simply buy.

Your target market is other developers or IT users, then the chance that your MVP might be copied becomes much higher.