No, I don't think bitcoin is endangering our environment. Bitcoin was founded in 2009 and was the first ever concept of decentralized cryptocurrency. Decentralization is very promising in terms of speed and usability. Since then bitcoin has seen a rapid growth along-with many other altcoins. I believe technology and globalization are two different ways of progressing. And this may be the reason that bitcoin is the hottest topic of December '17 as it gave people 20x return if they would have invested in the starting of January '17. Bitcoins are limited in supply and can also be mined. As bitcoin rose, difficulty to mine a single rose exponentially too. But some people saw GPUs are more efficient than CPUs , so they made ASIC (application-specific integrated circuit) miners based on SHA-256 that can process at very high hash rates. So many people started mining and those saw results didn't wasted their time and bought another miners according to their respective profits. Those people made huge money and now many cloud mining services are also available. Steem is new market but is very promising and legit. So surely steem is better but bitcoin is the first ever cryptocurrency.