We must let people know we can do X first

Some may question or even challenge me for revealing my capability explicitly in getting something done, even though I have not and probably nobody has done it before. 

I argue that we must let people know we can do the thing (X) first, earning their trust and empowerment, before actually starting to get it done.

If we, who really know how to get X done, do not actually get X done, and worse, let those who do not know how to do X to finish doing X and produce negative outcomes, then we may lost the opportunity to get X done in the future.

So we must first let people know that we can get X done, and then seize the opportunity to do X. The positive outcomes would eventually make people believe that X is doable and practical.