Sense

Chem eng base. Data brain. Design eye. Blockchain heart.

There is such a thing as a 51% attack, but a bad actor would need to have 51% of hashing power which would  take a phenomenal investment. 

Bitcoin would have been much more susceptible to this attack in the early days, but this has never happened. 

Is it still worth it ? It’s the most secure form of mining. There has been a big push for bitcoin mining with green alternatives and progress has been made.

PoW has really stood the test of time and i think its safe to say that, with greener energy, it might just be evolving the right way.