Although some people don't like to watch football alone, that's why they usually go out to viewing centers where they can watch and argue with other football lovers too. From my observation, a large percentage of people who watch football at viewing centers doesn't have a subscription for the channels that will allow them view the match in their house. It's possible that they have television in their homes but they don't have subscription.
If subscription is the only problem as to why most go to viewing centres to watch football, then I think all the viewing centres will be less populated on match days compared to the way they usually are.
Even if someone doesn't have a subscription to their TV, they also have smartphones that don't always lack data; they can stream it online, and if the television they have at home is a smart TV, they can connect their mobile phone to the TV for a wider screen.
Let's also say subscription is the problem. If you calculate the cost some people spend on just watching football, you will know that renewing their subscription is nothing compared to that, as some buy drinks, carry friends around, and pay for transportation just to visit their favourite viewing centre.
I know it will be difficult for you to believe but although it depends on the country your are based, but I know that in my place, if you go to watch football in a viewing centre, you are only required to pay not more than $0.4 to $0.6 or you purchase a bottle of beer which could be less than a dollar. Which you want to do a one month DSTV subscription for all the football channels, the charge is about $20 which a high percentage of people you see in viewing centers can not risk that huge amount for subscription.
They prefer to pay $0.4 to watch a match than pay a $20 one month subscription for their TV.
Yes, many of them have smart phones to stream the match online but I still want you to understand that a very large popular of football lovers doesn't like to watch football on a tiny screen, they prefer a big screen like TV or monitor. Secondly, some of them have tried streaming platforms but they probably don't know the right one because about 80% of platforms that claims to host live match all sucks.
Another thing to consider is the stability of power supply, some of them doesn't usually enjoy steady power supply, therefore they go to a viewing center where they will not have issues with power supply. Some of them you see there don't also want disturbance and distractions from their siblings or family at home.
I will say there is more fun they derive from watching with others compared to when they are home alone, while some people use that as an excuse to leave home.
No doubt but believe it or leave it, many people you see there are there because of the issues I have stated in my first comment and also the few point I also outlined above.