The better question may be why can't you find startup co-founders? I can see two main reasons why this might be the case. First, no one else sees the same opportunity. If this is the case, you may be on to unique value that no one understands, but that could also include the potential market. If no one else sees the same market opportunity you do in your startup, you will want to do more research to ensure you truly have a marketable idea.
The second reason is that you don't have a big enough network to find co-founders. This will also be a barrier to launching a startup. For a startup, the network of the founders is essential for both tapping into experience / skills the team does not have as well as for helping develop the market. If this is the case, building your network should come before building your startup.
I hope this gives you some useful things to consider. Let me know if I can be of further help.