No, it is not a scam, betting has never been a scam, sometimes the concept of betting can be interpreted through misunderstandings because there are people who have had bad experiences in casinos that turn out to be scams.
Betting is not a scam but should I say it is a kind of entertainment or fun. In scamming, you cannot win, you will always be at the losing side. Unless they will want to make you win small and then collect major from you. From the layman's angle of view, we could say that betting is a scam. Even from the professional view, the house edge gives space for manipulations.
Now tell me: can you call something fraud if you accept to enter knowing how it works?
From this your perception. What if the process or working principle is wrongly explained to you and you ignorantly accept. Scammers make you believe what doesn't work works, what doesn't exist exists, what is done like A is rather done like B, all in an attempt to defraud you. If what doesn't work for everyone is scam, betting should be considered one.