I did an experiment on a WhatsApp chat of my friends. I asked who everyone was voting for. Most people responded publicly. Some didn't. I privately asked those who didn't respond if they would share with me who they are voting for privately if I kept their answers in confidence. They all responded they were voting for Trump. I asked them why they didn't post their voting preference on the chat. They all had different reasons why they didn't want publicly announce that they were Trump supporters. One was even afraid that someone would share a screenshot of his Trump support and he would lose his job.
Although my experiment is not scientific, I saw firsthand that there are "shy Trump supporters" out there.