Time is absolutely a construct, just like the iPad I’m typing this on is a construct. I really can’t be sure it exists, but the model I have in my head that I’m tapping on a large flat surface with my fingers agrees with my observations. If in my next tap I get a painful burning sensation in my finger and I hear the fire alarm go off I may need to change my model to consider that I was mistaken and I may be touching a what appears to be a flame instead.