Trust me, most of us will never hit that limit so clicking that button just means putting all your balance on it. Try it;)
Not exactly. Hitting the button shows max allowed bet on any market and it is not related to your balance. It is always a much bigger amount than any of us has on his account for big games like Champions League or Premier League. But if you are betting on some low liquidity market like eSports or challenger tennis, max bet amount can get real low. There was some eSports games where I could not have betted more then 3mBTC, good thing too since I lost most of those bets 