Sports betting and sports activity started about the same time, so it has always been a thing that ran along together, it's just now that the system is beginning to get corrupt and leading to match fixing, else for the decades that sports betting starts, there was no record of match fixing.
How do you tell there was no match fixing until recently? Modern football is about 160 years old, do you think this is the beginning of corruption in sports. We only get to know about corruption in sports because the victims were caught in the act, if they didn't find out the truth then maybe you might keep feeling like the game is without corruption. Match fixing has been a thing even in the past, it will always be a secrete among benefiters.