Bitcoin PoW is understood to be broken due to the technical knowledge to partake and the $capital costs to get involved. Even in developed countries, how many middle class people have enough $capital to pay a $60K monthly electrical bill, build a large factory in China and build three people to watch over the hardware?
Why is NXT's pure PoS not considered broken? Only way to forge realistic amounts is through acquiring millions of NXT and that costs six figures in $Fiat (which will become seven and eight figures if NXT capitalization increases 10 and 100 fold).
Maybe because mining and forging are not supposed to be a money making opportunity? They exist to secure the block chains, not as get rich quick schemes.
They need to be somewhat profitable otherwise people wouldn't secure the block chains and the networks are less secure, but IMO you aren't supposed to be able to make a living doing so. Providing a small supplemental income is enough to keep the block chains secure I think.
Sure, people with deep pockets may be able to, but even then it is only marginally profitable and they have to throw a lot of money at it to make a decent living. I think there are easier ways to make a living if you have that much money.
Btw.. I am still bullish on Nxt