Yeah the site is legit but as he mentioned the website didn't pay few people because they had earned profit. So if you bet 1 btc which is 1300$ approx and if barcelona wins you will get 1560$ which should be withdrawn and should not be used again to bet.
Read this also :
Regardless the nature of Bitcoin payments as a regulated operator we are obliged to ID verification, KYC and AML (anti-money laundering) procedures by the regulator at certain withdrawal levels.
We have stated this clearly in our Terms & Conditions page available here
https://sportsbet.io/about/general-terms-and-conditions3.3.3. Sportsbet reserve the right to carry out additional KYC verification procedures for any withdrawals exceeding the equivalent of 10 Bitcoins or 2300 which ever is lower, and further reserves the right to carry out such verification procedures in case of smaller withdrawals, as demanded by our gaming license. Account Holders who wish to recover funds held in a closed, locked or excluded account, are advised to contact Customer Support.
On that case Sportsbet.io gave back the deposit the guy made (15 BTC), but he lost the profit made (6.5 BTC), didn't have losses, but didn't have any profit... On his case Sportsbet.io applied the argument to use additional KYC verification procedures because the withdraw was superior to 10 BTCs and said the guy failed on this procedure, etc...
If you are betting low and aren't dealing with much money I think you are safe without complications on procedures... Althought the nasty situation, the site is working, paying and continue having some reputation, I would use that for gambling. But if the mentioned situation bothers OP, he should look for another site.