That logic is silly. Overeating, binge eating, and consistently practicing poor diet habits that lead to obesity aren't necessary, beneficial, or difficult to avoid. These are habits and activities that serve no purpose, are anything but productive, and are very obviously detrimental to ones health. Most everyone knows that if you eat nothing but Cheetos and cake all day and never exercise, you're going to end up overweight and unhealthy. You use football as an example, but those two activities - overeating and playing sports - aren't comparable. Sure, you can get injured playing football, but you can also get injured walking down the street to get the mail. Most people don't leave a pro or casual game of football with injuries that alter their overall physical health for the foreseeable future, nor has there been an excessive amount of research done on the negative impact of playing sports - quite the opposite, in fact, as participating in physical activity is proven to be great for your overall health. Using your logic, we should all keep ourselves in a plastic bubble because, on the off chance we do something to injure ourselves, someone might have to pay the bills if our insurance doesn't cover it and we can't afford the treatment.

I can't speak for everyone else, but I give a shit about people practicing poor life choices - especially to the point of obesity - because I've seen first hand how it can effect others. My dad has been overweight my entire life, and growing up knowing that if he doesn't change his habits, he won't live past 50, and seeing how difficult it was for him to participate in things with my family and I - going for hikes, going for long walks on vacations, playing sports or active games - really took a tole on my mom and I. Having my entire family concerned for his health, and all the negativity that surrounded his diet was really hard to grow up with. A lot of families with obese parents raise obese kids, which sets them up for health issues and other failures later in life. Aside from being a financial burden on society, that shit effects their families, their jobs, and a ton of other things, too. I don't look at smokers and applaud their behavior, either, don't get me wrong. But OP has a good point. There's no benefit in supporting bad behavior. No one says "it's okay to do heroin, keep on keeping on." so why should obesity be applauded and supported? Sometimes you need a push, and you need people out there making it clear that what you're doing isn't healthy in order to really understand why a change is necessary.

tl;dr - your logic here isn't really valid, you can't compare the small chance of a sports injury to the obvious harm in bad diet habits.