The thing is, you should only hope for the block reward of 12.5 since the halving is just in the corner and block rewards cuts into half as well. I've seen someone got lucky with an Antminer S3 in 2014 (IIRC), but with as little as 1.5 GH/s is surely mission impossible for you. On a side note, it's nice seeing someone positive
I like to be positive. :-) Everyone, but everyone is saying.. "Don't mine, waste of time, Oh No, you aren't still mining are you..., give it up, you'll go blind..." but I don't care. I still see thousands of people on just this forum - so someone's still doing it other than me. If I wanted to run a business and make a profit, I'd run a street snack stall outside a Shanghai Metro station.
If I want' to enjoy myself fiddling with IT stuff, and seeing how it works, bitcoin mining is a whole field of interest in itself.
For example - I have a spare, very old, Toshiba L630 Laptop running Windows 10. I put the Windows App "Bitcoin Miner" on it the other day, created a Blockchain wallet and let it rip. They pay each time it clocks up 2,790 Satoshis. In two days I made GBP 0.02, about 3 cents US. Somebody else sent me $0.42 (in btc) I've no idea who or why. And someone else sent me a few cents worth of Sartoshis for signing up to their newsletter.
I purchased an Antminer U1 from ebay, new, for about £37 I think it was, just to try it out with MacMiner. Setup is a bit iffy, but it's running. Anyway, I looked at slushpool's payout program, where I had a pool link going, and they apparently don't pay out until you have practically mined a whole bitcoin. Which in my case will take about 7 years... I mean who cares. I can't wait that long for anyone's payout. So I thought I'd just let it run on the ckpool's lotto web site until I think of something better to do with it.
and mean time, I'm learning a lot about bitcoin, and bitcoin technology. I'm having a lot of fun, and it's helping me avoid doing all sorts of other things, like earn a living, have a social life, ... I could care less about profit, power costs, and ROI.
So at the moment, 2750 Sartoshis is worth about £0.02 - if Bitcoins get scarcer and harder to get, the value will only go up, so that 2 bits worth may well become, well, maybe even 4 bits !!!
One has to stay positive in this life :-)