You are right, nowadays it is very Common for most players to go for the sports betting option since things there are easier to win money, while in casino games you depend a lot on luck, but as for these two areas of casinos I agree that they are similar in the activity that the player can perform.
Neither of them is given to any gambler as an easy treat. Just like you have tons of options on the casinos, you also have them on sport games and there's no argument about that.
You have a point, but still, if you are well-experienced in sports betting and you confine your gambling scope to certain options, you are better off, as you can win more, appreciate your skills and be proud of your decisions, and can be consistent as well. Can you say that about casino games? Heck no! Casino games are not a respecter of how brilliant you are, nor the skills you've gathered to play it, the house reigns supreme, and they only let you win when they want. You are playing against certain algorithms here that "you cannot beat," you can only be lucky to be happy with it. This is unlike in sports betting that you and the house have a 50/50 chance, as they do not have any influence on the outcome.