Is it profitable? I bought one from Amazon and with default settings, about 10Gh/s I earned 0.00000716BTC the 1st day. So in about 5 years I will earn 0.01BTC (without calculating power cost) which is way too low.. If I did not do any mistake or misunderstood something it seems there is no point to use it.
Even if I increase frequency eg with 25Gh/s I will earn 0.01BTC in 2 years...
Please tell me if I am wrong.
With the current bitcoin difficulty, hashing at 25GH/s is not profitable. So yes, there is little point in using it. Your best option is to point your miner to solo.ckpool.org. It's like playing the lottery. You're unlikely to win, but if you hit a block, you get the full block reward.