Since Techelet is a De’oraita Din - why doesn’t everyone wear it even if they are not sure it’s the Techelet (based on Safek De’oraita Lechumra)?

There are Poskim that write that you need a better certainty to use the Techelet that's in use today, and that is the opinion of most of Gdolei Yisrael. There are also Poskim who write that there is nothing to lose. That's why Safek De'oraita Lechumra isn't used here. Rabbi Ro'i Margalit