"I was contemplating virtual meetings and came to a conclusion that they are better than in-person meetings as they cut (down on) costs." Use either "cut costs" or "cut down on costs" "in-person" is hyphenated. However, maybe you could use "face-to-face" instead. :)

I was contemplating virtual meetings and I came to the conclusion that they are better than in-person meetings because they cut [down on] costs. (The second "I" is not absolutely necessary, but it makes the sentence clearer. "As" means "since" or "because," but it is not as clear as these two words because "as" also has other meanings. "In-person" has a hyphen because it acts as one adjective.