Why 5-10 years?

At current rates, price per equivalent output is dropping at 99.9% over 5 years.

That's basically $0.01 in 5 years.

Does it really need to be that cheap to be worth it?

Keep in mind, $0.01 in 5 years is worth less than $0.01 today.

Wow that's incredible! Could you show your work?