Every government that regulates gambling can allow betting on some events, they don't want casinos in their country but they can allow football or boxing or even horse racing betting, it's up to the government what kind of gambling they would like to regulate but about your thread football is a sport it was not created for people to gamble, gambling operators just use football for people to gamble.
Agreed, the OP seems to have it backwards, it gives me the impression he thinks that sports exist just for people to gamble, when it is the other way around, people enjoy sports on their own and there are a few that like to spice things up a little bit by also gambling on their favorite sport.
And since governments make the laws they can decide if they ban gambling completely, if they allow some gambling games while banning another forms of gambling or if they allow almost all forms of gambling, it is up to them and while I would prefer that most governments were progressive on that topic at the end of the day we need to follow whatever regulations we have in our country, fortunately for me I live in a country in which gambling is allowed so I do not have to hide my preferences at all, as it happens to some other members that live in other countries.
the OP needs to revisit his post and maybe differentiate gambling vs sports. because he only provided the definition of gambling but he forgot to post the definition of sports. so maybe, he will understand that sports itself is a stand-alone industry
so yes, sports can exist even without gambling. and since every country has their own stance towards gambling activities, they can impose whatever they deem necessary - according to their religion, culture etc.
it is not the case that if the sports is legal then gambling on the sports will be legal as well.
Agreed, gambling and sports are different industries. Here sports industry have the ability to move on its own. The gambling industry is much dependent over the sports industry, but for the same OP have misunderstood that gambling need to be legal when the sports is legal.
As said governments have different policies which portrays why gambling is illegal in the country. Also there were more sports/games are illegal in different countries. For example cockfights, there are countries and people yet conduct those games and gamble over it.