I have seen tipsters that are consistently profitable.

Most experts who claim that they know the game inside out and have certainty in the result of each game is lying to you. Most profitable tipsters that I've come across do not proclaim this, but rather place bets on +EV propositions that over time accumulate to a profit of many betting units.

That said, don't go out there and blindly pay for a tipping service. Make sure that they have a verifiable edge and track record first.