But my electric bill is like $30-40/month, Why would I want to shell out $12,000 for something that will become old tech in couple of years like the 1 powerwall.
30-40$ is probably a very small apartment. A house (2 levels) in Quebec during winter can go easily around 500$ because of the constant heating required.
Cooling a house during the summer in Texas can easily cost the same amount if not more, and you get a ton of sun during that time. The point is that for single family homes electricity does not usually cost $40/month.
But the price for the equal amount of power walls needed for a bigger house vs a small 1 bedroom raises too, according to the calculator on their site it will cost $30k+ to install it for 4 bedroom house.
It will take most people 20-30 years to recoup this in terms of an investment over wholesale energy costs at current rates. It is, for the present a gimmic.
The funny thing about solar... it's not constant. Half the day is night... then clouds/rain/etc. 24/hours of electricity is for those dry periods.