Some people would love to watch their favorite team at home with their family, some at a bar while their are others who would love to go to a viewing center.
Let's treat each one of the places one after the other, if we are in the situation whereby our family are also in support of gambling and have interest in watching some of the sporting activities, live matches and many others, we can always make subscription to watch at home together with our family members, same applies to betting a game if we so wish to gamble as well, but going out with friends and watching at the viewing center is not what many could accept doing, especially when they have family and responsibilities at home, they will rather use their house and family for that purpose.
You have a point there, but we still need to consider that it is not about betting in this regard, it is about watching the match. You may bet your thing even if your family is here because it is not all that you do on your phone they see, and that is if you want to engage in the live match betting. Needless to say, you can conclude on your betting options and even place all your bets before the time of the match, which means that the family members will not know about it if you do not want them to know.
As for watching the match, it all depends as well, we have different family settings and even different preferences within the same family. The husband may like watching football and the wife may not like watching it, and of course, the children of younger ages will not leave their home to watch football in most cases. But if they love it, the father, for example, may decide to be watching it at home because of them. But if the father is such that his the only one who likes watching football, it is not a big deal for him to excuse himself to watch football while the other family members watch whatever they want or engage in other activities.
That by the way, it is a school of reasoning. In another school of reasoning, the personality of the person matters. If I am an extrovert, I will always love to watch it outside, which is the opposite of a private person or an introvert. Personally, watching football outside is not my thing, except it met me coincidentally in an honourable place where I can easily and freely watch the match. If not, I always prefer to watch my thing at home as "no place like home."