No. It is 4 BTC per year. If you can earn that much bitcoin per year, you can do more than gambling, I'm telling you.
Do not waste it to gambling. Also, there could be no sports matches that you can be 100% sure of winning.
That is right. However, from time to time there are really good odds (compared to the risk) for particular matches. If you could identify those bets then you could make good gains. Of course, it is never 100% secure. But nothing is 100% sure. You could invest some in promising altcoins but if the dev runs away or there are security holes in the good then price will collapse. Then the safest way is to hodl your coins.