Money to be made?

[NL Newbie]

Hi guys,
Just trying to gauge how profitable sports betting is. Who are the losers, since arn't most bets Vs the house?

Also with a bankroll of say $100, what profits can you expect on that? How about $1000? Is it a fixed percentage or would profits be exponantial?

Thanks - Just widening my "Gambling" range from just poker.