Frank II, Most people just don't understand risk or chance. That's why people throw billions at lotteries every year just knowing they will win and they never do. They just don't understand that the whole system is rigged (well, rigged is not the right word because lotteries are not rigged, but the chance of anyone winning is so small it might as well be) in favor of those selling the tickets so they keep as much as possible.
The risk of catching this virus is significantly no different at home or in most of the rest of the world right now. Walking through a shopping mall or a farmer's market, a museum, or any other public space, is no different here or there. If someone has the virus and you get too close to them for too long there is a risk and a chance you might get it. If you are washing your hands as suggested and wearing a face covering, your risk is diminished but never completely eliminated.
The only place that it is different is in the getting there and back through the amount of time spent on a plane. Several studies have shown that simply being exposed to any virus is not necessarily enough to infect you. It is repeated exposure to an infected person or persons shedding the virus in large numbers that will cause you to catch it. So if you happen to have an infected person on the plane with you, the total number of hours spent (8 to 10 for most international flights, varying due to where you are coming from and going to of course) may cause you to be repeatedly exposed to the virus in large enough quantity to get infected. Domestic flights are usually shorter, so the risk is lower but once again not zero.
This all results in people feeling safer traveling domestically because of the perceived higher risk of catching the virus during the long plane travel. Also, many people would rather be relatively close to home if they do get very ill because they feel they will have a better chance of reaching home (whether or not that last is true will depend on how sick they get and how soon they rush back home).
I am not a doctor, although I did play one on the radio once. I got the above info from various reputable sources on the internet.