Many people dismiss scientific theories because they are only theories

The term "theory" means a very different thing when used in everyday conversation and in science. In our day to day speech, we often use "theory" to mean a guess or unsubstantiated idea about how something works (as in "I have a theory that gremlins are hiding my car keys").

In science, we would call such a guess a hypothesis, not a theory. A hypothesis is a proposed explanation for an observation. In this case, I am proposing that the explanation for why I can't find my car keys is that gremlins are hiding them.*

The distinction between the words "Theory" and "Hypothesis" is very important because in science "Theory" does not mean "guess". I repeat, "Theory" does not mean "guess".