Saw many cases where cloudbet asked for KYC so yeah , but for sportsbet they don't usually ask for KYC unless they suspect something going on like avoiding betting limits , suspecting double spending or abusing the promotions like the price boost
they ask for KYC for large balances as well , but I know some guys who had like 0.5 BTC with them and they didn't ask them for KYC
At how much do the sport betting sites usually start getting worried and request for your ID and documents? I bet small, so I wouldn't know.
And I've never seen so much people complain about it than here at BCT. In online poker it's like just another thing to do if you wanna start playing at some site and be able to withdraw your money. Lol.