You may not be able to persuade the general public to believe that tai chi chuan is a credible martial art.
But you can still train the art properly yourself.
The main thing is to adhere absolutely to the guiding principles of the art.
These were outlined in the Tai Chi Classics.
If your art deviates from these, then you have gone astray.
Seek tuition from a teacher who is committed to training an art that applies martial skills in a thorough and convincing manner.