I use a laptop as a main computer And the desktop we have has a cheap $60 graphics card. It won't mine anything. I am just wondering what I am missing here. With the calculations I am doing with 72GH/s that would be 83k worth if bitcoins a year. I know it must be wrong. I just don't know if I should even start trying to mine if I won't make anything. Also if the block thing is going down to 25 instead of 50 wouldn't that make bitcoins worth more?
I'm assuming that when you say 72 GH/s for $1200, you are talking about buying the new ASIC hardware. Right?
Here is the problem. They don't exist yet, and when they are finally shipped, everyone will get one and the difficulty will go up by a factor of 20 (more or less). Your estimate of 83k worth of bitcoins will drop by a factor of 20 to 4.2k. And don't forget that the block reward is being cut in half, so your 4.2k per year is really 2.1k per year. So it looks like you might be able to make a profit, but it won't be anything like 83k a year.
Anyway, even if you order one now, you won't get it until next year. You might as well just mine with what you have now and order one next year.
Finally, the halving of the reward will have no significant
direct effect on the value of BTC. There is a lot of guessing about what will happen when the reward halves, but nobody really knows, and nothing happening is just as likely an outcome as anything else.
Also, why is it so important to make money mining bitcoins? Why not just do it for fun or as a learning experience? Why do you want to make it your job?