If it is legal it is ethical.
I add that I never bet. Because the odds are not favourable. And there is no magic.
My view is educate at school (apparently this happens) then, like beer, loose women/men, stocks and shares, if it is legal, fill your boots.
If you want, on the other hand, to...
Don't listen to radio 5 now. I have never heard so much shite. Anyone gamboling on 32 red because roonz has 32 on his silly derby shirt back deserves to loose all their gammon money. FFS.