I don't think you should worry,if you have not received an official email from Stake that your account is restricted and not only the sport section of the site the withdrawals should pass through if you haven't violated any of their terms and conditions.
We are talking about Stake here who gives like near 1 million dollars in bonus when is Christmas time like they did last year,I don't think they will care much to restrict an account for 80 mBTC which you claim to have won.I doubt they will put their reputation at risk for such ridiculous amounts for them.
How do you know that? You've seen testimonies about official emails sent to customers whom they locked their funds? Could you share them with us here? Because CMIIW but rickmart's account has obviously been restricted without any email nor notice.
Moreover, even if Stake is really sending "official emails" for that, like a professional or regulated sportsbook, don't you think it's a little bit late to care about it when you receive one? I don't think they will notify the user before locking his funds.
I try to bet as much as possible on promotions proposed by Stake but I never cheated (back multiple sides, etc ...). I usually take some info from tipsters and I bet often on lower leagues to have value bets or surebet sometimes, but frankly if betting on exotic league or markets is suspect in this case they might as well not propose these markets.
I never use large stakes for my betslip, most of the times from 1 mBtc to 3 mBtc and as far as I remember I have not set any betslip with more than 15 mBtc.
You're obviously an honest customer, but it's not enough for being a good customer in their eyes, they want to earn money from you, not giving money to you. You've maybe just been lucky for the moment and you will maybe lose all your winnings in the coming months, but obviously they don't want to take risks. They prefer "showing you the door" as Maasdamer.