I suggest you do some research into how scientists get to the age of our universe. It's not a random calculation. It's not a guess. It's based on solid science.

Okay, so you have deep respect for people who insist on something that is absolutely factually false, but none for people actually doing the work of attempting to figure out the truth.

The reason we say know is because we are pragmatic, saying "the current estimated age of the known universe validated by the currently found evidence is:"
Science never knows the "truth" and never claims it knows the absolute truth (absolute truth is for religions), the knowns in science are based on the best evidence…

True they don't have clues... they have evidence.
Just curious, do you know the age of the universe or just claim that other people can't know the age of the current universe?