#1, I don't think it's relevant that you think that segment of the population is irresponsible. We are talking about adults and taking away their freedom. I personally would rather see objective facts, not opinion.
>people in this age range often unjustifiably act like they're invincible
#2, I think you are wrong about their invincibility in this case. 330 people under 25 died of covid as of August 20 [0] (most with comorbidities), out of a population of 104 million in the U.S. [1], that is 1 out of 346,000 (edit). This is not high on the list of dangers for that age group.
You should attempt to justify your imposition on them without smearing them. Young people are not in danger from this disease are being forced as a group to make significant scholastic, social, and economic sacrifices for those who are too afraid to self-isolate on their own.
EDIT: Maybe the focus needs to be on vulnerable populations, and not young people? What is the goal here? Are Colorado hospitals overwhelmed? There's no proof that lockdowns otherwise make a difference.
[0] https://fox8.com/news/coronavirus/new-cdc-report-shows-94-of... [1] https://en.wikipedia.org/wiki/Demographics_of_the_United_Sta...